CM028 gearbox problem

[mike1045]

I just inherited a CM028-S as it packed in on the previous owner and he couldnt be bothered to do anything about it. The gun is doing nothing at all when fired (yes the battery is charged!) no clicking noises, no nothing. The fuse appears to be alright although i have to admit i have no spare at the moment but the filament looks to be intact anyway.
Another thing that confuses me is that when the fire selector is on safe the trigger still pulls all the way back.

Any help, tips, advice or what not would be muchly appreciated!

[dfrear]

Re: CM028 gearbox problem

Does the motor spin if you take it out of the cage (assuming it has a cage with it being an AK)?

[mike1045]

Re: CM028 gearbox problem

Semi-success! I took the motor out and it worked fine, and it works fine when i put it back in the gun. None of the wiring to the motor looks damaged or out of the ordinary in any way so i havnt got a clue.

The selector is being a pain though, once you have dropped down to semi, the gun will still only fire in semi once you go back up to full-auto and even safe. I have found that if i take the top part of the receiver off and turn the selector arm a good 90 degrees up and put it back into safe again, it all works fine until you put it back into semi.

Any ideas?

[mike1045]

Re: CM028 gearbox problem

After further faffing (breaking), the selector arm is now 'limp' and is currently hanging about near the trigger!

[dfrear]

Re: CM028 gearbox problem

It sounds similar to a problem I had with a selector arm on a Galil SAR. You may not have put the selector components back together properly after stripping the gun down. I think (complete guess really) that they use a series of small plastic gears, get them lined up wrong and it wont be able to engage auto or safe after changing. It should be a simple fix if you haven't broken the parts (in the SAR there was a metal part which was stripped)

[mike1045]

Re: CM028 gearbox problem

Upon further inspection, the little cylindrical mount that the selector arm sits on is quite mangled so when i move the arm, that is really all i am doing. I will try to file it to resharpen the edges but due to it being made of some sort of soft cheese i dont think it will help much.

The components on the side of the gearbox seem extremely loose, which means that the vibrations when firing cause it to drop down to semi anyway, is there anyway of resolving this as it doesnt seem as though there is anything externally that needs tightening.