AEG inconsistently going full auto when selector in semi

[Wombat Six]

My KWA M16BR is inconsistently cycling in full auto when the selector switch is in semi auto. Sometimes you pull the trigger and it cycles once. Sometimes you can do this a couple of times in a row. Then you pull the trigger and it goes full auto. Then you pull it again and it's back to semi. Sometimes the trigger locks up. Rinse, repeat.

I believe that I have the selector plate correctly aligned with the switch because the "SAFE" position locks the trigger out and the "AUTO" position, well, is. Is there some magic trick involved in the reassembly process that I've totally botched up? Something easy I can look at and go "Yep, that's not the right way?"

The battery is fully charged, the motor height adjustment has been zeroed out and fiddled with to no end (and has been reset to zero), and the AEG is otherwise performing flawlessly.

ADDENDUM: The AEG only cycles when the trigger is held down. It ceases cycling if you release the trigger.

[Nox]

Hey Wombat, are there 'fingers' in the selector area that contact the selector plate?
I've only worked on one KWA and I can't remember offhand.

[Nox]

Alot of these problems can come from several points -
If there are fingers in the selector area that make a complete circuit through the selector plate, then those may need to be bent back in towards the gearbox slightly to releive the problem.
If there aren't fingers or tabs there, it could be because there is debris in the selector plate area like either metal shavings or even oil in between the contact areas that could be 'shorting' the slector out.
You can try to wipe the selector area down with a rag or a brush to try to dislodge anything that might be there thats causing problems.

[Wombat Six]

Affirmative. Two of them. Both come into contact with the plate at the same time. Based on my rudimentary understanding of the V2 gearbox, this is not as it should be.

[GacktC]

It is causing by the selector plate most of the time.

[CommieHunter]

The trigger switch itself, the connector that slides back and forth, may not be sitting right, so when the cutoff lever engages, it misses the trigger. That'd be my first guess.

[Wombat Six]

Thank you gentlemen. That confirms a suspicion of mine. Looks like I have another evening of gearbox teardown ahead of me.

[Wombat Six]

So before I go to all of the trouble of reassembling this thing, let's poll the audience. Here is the inside of my gearbox:



Left side, just below the bearing, the little latch looking thing. When I disassembled the gearbox, I discovered this particular item was "loose", in that it was not screwed down tightly. Is this the piece to which you refer to as the "cutoff lever", CommieHunter? Would its looseness be a cause of the previously outlined symptoms?

[Seagreen]

If the notch gets worn (and usually it isn't greatly apparent), you'll start cycling in full auto, when you have the selector on semi. This is almost definitely the part that is creating your cycling issue.

[Wombat Six]

Sweet. Now to grease everything back up and reassemble this, for great justice.

[Wombat Six]

Mischief managed. Retarded design is retarded. But working again.

[rockettravis]

Keep your cut off lever "loose" to where it can move freely! slide your selector plate to where it barley touches the safety engagement arm. now make sure that your cut off lever is fully engaged at that point (meaning pushed toward the center of the bearing. If not your linkage has the problem.)

[Wombat Six]

It's already fixed, but thanks for the guidance. The lever can move freely, but before I tightened the screw down, it moving side-to-side about 1/8th of an inch.