[Hectic]

first problem is u posted this twice lol.
after that is that u shoulda litened to the folks who told u not to open the gear box.
okay now ill stop pokin fun at you, it could be alot of things but id say the loading nozle and tapet plate are likely the issue if its not always feeding and has low fps.
tho it could be any number of things.

what kind of gearbox is it?
mechbox.com has videos to show you what to do to assemble it properly.
the site is down but there youtube is up still.