So some details would help. Sorry! After finding a faulty transmission 2 weeks ago AFTER I pressed it into the pen I decided to start testing them before I put them in. Today I took a transmission out of the bag, held the brass end and twisted it, it seemed to work. I pressed it partially into the lower barrel. I put the cartridge in, then tested to see where the tip ended up. the transmission would not rotate as far to retract with the cartridge in. I took the cartridge out and tried it again, it seemed normal. I put the cartridge back in, and it seems like it doesn't want to rotate as far. It needs to be pressed in further but I am afraid it won't retract the tip all the way.
Another completed slimline I have rotates more when you twist it. I took another transmission out of the bag of another kit and it seems to do the same thing as the one that isn't working.
I am not sure I have used these kits before, my other slimlines have come from Woodcraft, so maybe I am worried about nothing?