My lathe is not a Laguna, but I suspect that quill mechanisms aren't all that different.
My lathe has a handle that locks the quill in place so that it cannot advance or be withdrawn when it is engages. That handle is on a screw that is supposed to ride in a groove machined in the side of the tailstock ram. The idea is that the screw riding in the groove prevents the ram from rotating, and when the screw is tightened, it locks the ram in position. However, if the ram twists slightly, the screw can iinadvertently engage with the side of the machined groove, making it difficult to move the ram in and out.
Periodically, its a good idea to disassemble and clean the tailstock quill. Whether the quill should be lubricated is a subject of some controversy - if you choose to use a lubricant, select something either a dry lubricant (graphite) or a lubricant that will dry after being applied; using a lubricant that remains 'wet' means that it can collect dust which will only make operation of the quill more difficult. I use white lithium grease - the stuff sold for lubricating the rollers on garage doors.
So if you haven't done it already, you might try taking the quill apart to see if you can determine what is binding., and while you are at it, clean the ram and think about applying a lubricant. My experience is that if that screw starts binding on the edge of the alignment groove, it can leave dings in the metal that can make it difficult to advance the quill. Those dings can easily be filed off,.
Having owned (well, I guess, still "own") a Laguna 1524, I can say that not all tailstocks are created equal. I finally gave up on my laguna after nearly a year fight with it, and the manufacturer to resolve what I felt was a critical design flaw. Most tailstocks, including the Laguna 1216 to my knowledge (and I can only hope this is still the case! more in a moment), simply have a round hold a hair larger than the quill bored through them, a quill with a thread tapped through it for the leadscrew, and a locking lever. This design ensures that the quill is as supported as possible, with as little play as possible, throughout the range of its extension.
Laguna introduced something called Precise Point with the Revo 1524. The design of a Precise Point tailstock is different than any other tailstock I've examined (and at this point, because of the issues I've had, I've disassembled and reassembled tailstocks from Nova, Jet, Wen, Laguna and now PowerMatic). The 1524 tailstock has a rounded square hold bored through it, with ample empty space around the quill. The tailstock has a small "cap" on the front (and back, in fact) that is maybe 1" thick (slightly less in my measurement), with a round hole bored through it for the quill. This cap bolts onto the front of the tailstock, and the holes that the screws pass through are bored larger than the screws to allow for some freedom of movement. This movement was supposed to allow "precise pointing" of the quill, so that you could EXACTLY point the tip of a live center exactly at the tip of a dead center. Once this alignment, usually made with the quill fully extended, was achieved, you lock down the screws that hold this little cap in place.
The idea is nice...the implementation, IMO, is an absolute disaster. The fundamental problem in my experience is that the quill is only held in place by the leadscrew and the cap. There is absolutely nothing else in place to hold the quill stable. The only time the quill is truly stable, is when it is retracted...as it is extended more and more, there is less and less leadscrew to support it, leaving only this barely 1" thick piece of metal. The thread tapped into the quill is usually of poor tolerance, so the leadscrew is not a very tight fit within it. The hole bored into the cap is also not of the best tolerance, although better than the screw. These two factors together generally mean that though these two things are the only things that support the quill, they don't really do a great job. My honest opinion is that this design leads to more problems than it solves, and that the "precise" pointing it aims to offer is neither truly able to be realized, nor is it enough to warrant the other problems the design introduces.
Problem number one is that when the quill is fully extended, it droops a little bit. So, once you have aligned the live and dead centers, when you retract the quill again, its actually slightly misaligned. This isn't great, but the misalignment isn't terribly large....at first....so its not a big problem. The problem occurs, though, because there isn't much supporting the quill...so it has a bit of a wobble. Its not perfectly rock-solid stable...like you would expect from a quill. Like you will GET with pretty much any other lathe...
Problem number two is that because there isn't much supporting the quill, and because what is supporting the quill isn't machined with tight tolerance, any off-center contact between a live center and a rotating piece of wood can slightly jerk the quill around. This, in turn, seems to wear at the hole bored through that little cap, and worsen the tolerance between the tap through the quill and the leadscrew. Over time, the wobble in the quill gets worse. The droop...droops more.
Problem number three is that after turning enough things, you have increasing wobble in the quill, and are constantly readjusting the cap to try and keep a live and dead center's points dead pointing to each other. This becomes pretty much a per-job thing. However, with increased quill droop the hope of any kind of accuracy in your pointing diminishes to near zero. The inevitable result is that almost any time your live center, shoved into this droopy quill, contacts any moving piece of wood, there is a chance that it will contact off center (by as much as half a centimeter, in measurements of my own experiences with the 1524). That off-center contact, if it is large enough, can cause a significant vibration. I've had things fall off walls, the lathe walks itself across the floor, etc.
In short, Precise Point is anything but...and the problems it introduces over the long term are far, far from worth the potential minute gains you might have in terms of exactly how dead accurate the pointing of a live and dead center to each other might be. The actual viable range of movement of the live center point is rather small as well, maybe at most a millimeter or slightly more off dead center...any more than that, and the quill ends up at enough of an angle that it binds in the cap and just gets locked into place. So its not much in the way of adjustment potential...basically a 2mm diameter circle around the point of the dead center without binding the quill.
Laguna seems to have ghosted me, so I don't have much hope for my issues ever being resolved. I have, however, implored them on numerous occasions to never propagate their Precise Point technology beyond the 1524. I've given them video examples of the issues I've run into, extensive written explanations of the problems. They have sent me multiple new quills and tailstocks to test...but none were ever actually redesigned. The only thing they did do at one point, was send me a new quill assembly (with the locking lever, 1" cap, and quill) that also included this little ~1mm thick plate of metal with a square protrusion in it that was supposed to fit into the groove in the quill where the locking bolt fits. Supposedly, this was going to add enough stability to eliminate my problems... This little plate, is exactly what I can see in the photo in the original post, to the back side of the quill as it is oriented in the photo, a little black piece of metal with two screws.
My experience with this little piece of metal is that, rather than solving any problems, it introduced one: Binding of the quill! When I have that pressed into the groove on the quill far enough to provide any value...the quill will usually bind on it, and it is hard to either extend or retract the quill when it hits a binding point. When that piece of metal is backed out enough to avoid any kind of binding throughout the extension range of the quill...well, it pretty much provides no useful value in terms of stabilizing the quill. I also found that with the disastrous tailstock design of the 1524, over time, due to the way the quill gets jerked around by a rotating piece of wood when in contact via a live center, this little piece of metal gets worn down as well, providing less and less value over time anyway.
So...to distill all that down. Try taking off that little black "clip" and see if you can more freely extend and retract the quill.
