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Lammy1000

Piston Binds in Cocked Position

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My Cyma AK74 048 makes a screeching noise and the piston gets stuck in the cocked position until the anti-reversal latch is manipulated. I opened the gearbox and did a thorough inspection. The spur gear has one missing tooth on the outer teeth, everything else looks great. Could this possibly cause the piston to bind in the cocked position?

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Take apart the gearbox.

 

Remove the spring/spring guide, and cylinder pieces, gears too, just so you can put the piston inside w/o any tension, close the gearbox, and put like 2 screws back in, and see if the piston can freely move along the inner gearbox's piston rails.

 

Some pistons are too large//gearboxes too tight, and will create this awkward lockup. Filing the rails on the piston and/or the inner gearbox shell is required.

~~~

 

If thats not the case, doing essentially the same thing above, except instead do this with the gears, and make sure they can rotate freely and the shimming isnt too tight....

 

The broken gear could be because either 2 above happened, and THEN the tooth broke.

Or, the tooth broke in the first place, and the gearbox locked up from the broken teeth getting into the gears and locking it up. which is just what normally happens in an AEG, things break.

 

Its when things break prematurely is when things are an issue. [Not including people throwing strong lipos into their guns]

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im guessing that when you open it up the spring isnt jammed stuck inside the piston or that probly wouldve been your obvious answer as to why

 

tight shimming and piston rails are a good answer

other possibilities are: too weak or failing battery, crappy or problematic wiring, metal connectors in the switch assembly being too gunked up, and a too weak or failing motor

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