WE Katana M4 Locking and weird half trigger pull

[Slodin]

Hi,

Just asking this for a friend of mine..he brought the gun over to take a look at what is wrong inside..I have never worked on a split GB before..although it's similar, it does have a few differences..although I have no exp on identifying worn cut-of lever or trigger contacts..

When shooting, the gun locks up, because I think it's just not completing the cycle thus gear not releasing the piston. Next trigger pull doesn't do anything at all, not even a click..until he opens the gun up and hear the piston release itself, and the gear teeth is facing upwards..what puzzles me is that the second trigger pull doesn't even make a sound like it's stuck or something. After putting it back it does the same thing. (These are completed with full trigger pull, 3 different full charged 7.4 lipo, checked for shorts which are none, wiring is all good, also checked gears spinning freely, piston is not stuck)

Tried these with the top GB shell off, so just gears and motor:
The problem he is having is that whenever he pulls the trigger fully on semi, the motor spins really weak, makes a audible click sound and usually cuts of the current way too early..not allowing the gears to complete a cycle. (it sounds like the click coming from the trigger area)

Whenever he half pulls the trigger on semi and hold it there (half pull), the gears just keep on spinning like it's on full auto and have more torque then a full pull...but combining with the symptoms mentioned above I can't make any sense out of it..(cut of lever bust?) holding it with a full trigger pull doesn't do this btw..

any ideas would be helpful

[Hectic]

I'm mot 100% on tue design of the trigger but what you describe sounds like a cutoff lever or trigger shuttle issue. When the gears rotate a cam activates the cutoff and lift the trigger shuttle to pop off of the trigger and return to battery.
(This is in a normal aeg I mean)
So if the shuttle is worn it could be popping off early. If the cutoff is damaged or bent it could engage a little early.
The trigger itself could be worn and the contact slips easily off.
If you pull the box and rotate the gears by hand you should be able to see how/when the cutoff occurs to get a better idea of what may be the culprit.