Semi Auto Not functioning VMG74

[TauterTwiggy]

Hey all,
I recently started teching on my AK74 and I recently put several upgrades in to improve it's performance, however after reassembling everything for the 5th time I noticed the semi auto has ceased to function. So I was curious if anyone else has done any teching on a V3 gearbox and could point me to the possible issue.

The selector lever and gears are correctly mounted so it would be something inside the gearbox at my best guess.
The safety works as well as full auto.

[luke213]

I'm going to watch this thread, since I've got the same thing;) But I haven't even taken the time to look at it yet to see what's wrong. So I'm curious what things will cause this on a version 3 since honestly I've taken apart a million version 2 boxes, but very few version 3 boxes over the years, and not had to fix these kind of oddball issues with them typically.

If you don't get replies, sometime in the next bit I'll be tearing mine down to see what the heck is going on and I'd be happy to throw up what I find. But it might be a little while since it's not one of my primary guns, and it's not a priority at the moment.

Luke

[TauterTwiggy]

I'm working on making this my primary field gun, so if I sort it out I'll make sure to post my findings as well.
I'm also going to post a video on You Tube of my tear down and reassembly. Sadly I stopped filming after 4 hours of fighting with a gearbox for the first time so I didn't film the flat hop I ended up doing as well but when all is said and done this gun will hopefully shine.

[Zzan]

I had this issue with my G-36C version 3 gearbox.

In my case I just needed to replace the cut-off lever.  I could not see any wear or obvious issue with the one that was there, but the issue went away with the new cut-off lever.
I did put the old cut-off lever in another V3 gearbox and the issue followed it, so I am fairly confident that the lever was the issue, just not sure why.  Not sure if there just isn't that much tolerance between new and worn or what.

The issue I had was no matter if selector was in semi or auto, it would fire full auto.  If you aren't getting anything on Semi it's probably not the same thing.

[TauterTwiggy]

It currently fires full auto in every position except safe currently so I will definitely check the cut off lever. hopefully I don't have to replace it given the gun is brand spanking new.

[TauterTwiggy]

UPDATE:

Disassembled the gearbox and replaced the stock cut off lever and spring with a "Guarder Version 3 Gearbox Yaw Control Bar / Cut-Off Lever (AK / G36C)", semi seems to work half the time now so may need a bit more tweaking but that definitely seems to be where the issue lies. It seems like the plate that controls the cut off lever doesn't pull far enough back so I need to add a shim or some plastic piece into the slot to pull it back farther.

Also upgraded the shuttle spring with one from "Matrix Reinforced Airsoft AEG Gearbox Spring Set for Ver.2 & V.3" since the original got a little stretched out which helped with my triggers stiffness and keeping the gun from staying in the firing position.

Also my AK74 might be way too hot now -_-; it can shoot through the sides,bottom,bottom edge, and top of an A&W can with ease on a M120 spring.