Old thread, so I"m guessing you figured things out by now.
My experience with slimline pencil kits is that the mechanisms are universally terrible quality. If they work at all, they wear out and break within weeks, or, at best, months after assembly. I have completely moved away from slimline pencil kits.
I think my experience matches the general consensus. I guess people are still buying them because all the retailers still have them. But I've never met someone who really likes slimline pencil kits.
There are a lot of upgraded pencil kits that are much better, though of course also more expensive.