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Nathan.g April 28th, 2019 23:08

AEG tappet/shuttle problem
Hey everyone,

Iím have no a weird issue that I have not encountered before and I am at a dead end. I purchased a modify torus gearbox, transferee all my internals, everything was peachy. Then, the back stop of the trigger blew off (not sure why). Since that point, I have been having a problem that resides in what has to be the shuttle slide / tappet plate (both Modify).

When I pull the trigger, it will pull the piston back about 3 or 4 teeth, then I lose all battery power. It feels like the shuttle is getting caught and not returning so the trigger is not even touching the shuttle after the first trigger pull. Up until I put the motor in the grip, the trigger works fine, motor spins, shuttle returns. I tried a few different triggers, swapped out the springs, and I was thinking a short might have been the problem so I re wired and still, same issue stoppingng the piston in the same place. I have not been able to get a single full cycle.

Any thoughts or tips would be appreciated. Very close to just purchasing a mkii at this point.


RainyEyes April 29th, 2019 06:36

Gearbox/trigger is off spec.

Disassemble the gearbox so only the trigger components and the shuttle are installed. Pull the trigger back so that the shuttle will engage the trigger contacts and then use a screw driver to pull the shuttle towards the top of the gearbox. Release the trigger but watch if the shuttle gets caught with the top of the trigger. If it doesn't you can file off a bit from the trigger or the gearbox so that the trigger will return to the original position more forward.

Similar to the above example. I think it's called "trolley float"

Nathan.g April 29th, 2019 08:02

Interesting - I will give it a shot. When you say file the trigger or gearbox, where exactly would I look to file the trigger? On the top where it catches the shuttle?

RainyEyes April 29th, 2019 09:37


Originally Posted by Nathan.g (Post 2064758)
Interesting - I will give it a shot. When you say file the trigger or gearbox, where exactly would I look to file the trigger? On the top where it catches the shuttle?

You can either file the top of the trigger so that the trolly can fall back into place with the trigger or the back of the trigger where it meets the gearbox.

If we're looking at my video where the right is the nozzle and the left is the bearings, the back of the trigger would refer to the protrusion on the left where the trigger meets the gearbox and stops the trigger from going all the way forward.

It sounds like you have spare triggers to experiment so do it on the one that's stock to make sure it works.

File it too much and the trigger won't push the trolley far enough to make contact. Too little and it slips off. A lot of experimenting will probably be needed and lucky for me a trigger swap worked for me so I didn't have to do that.

Nathan.g April 29th, 2019 11:48

Okay awesome thanks. Ya I have played around with 3 triggers so far - each being a little different from the other. I will try this tonight without the compression parts so I can get a better view. Figures my gearbox would break a week before my outdoor season starts..

Nathan.g April 29th, 2019 20:10

Alright so you were bang on with the trigger float issue - very much appreciate the help. I sanded down the base on the trigger so it would reset and now I am able to get it to cycle, but, it seems to take 2 trigger pulls to get the full cycle in semi.

If I pull slow then it works in semi, if I pull really show it fires full auto. Since the trigger is the only difference between when it was working I have to believe that the problem has to still lies somewhere in that area

RainyEyes April 29th, 2019 21:23

If it's not one thing it's another.

Your problem sounds word for word with mine...

Try adding material to the part of the trigger that makes contact with the trolley or replacing the cutoff lever if it's worn is a possibility.

Nuclear option: replace mechanical trigger with an electronic one lol

Nathan.g April 29th, 2019 22:52

It’s odd because full auto work so it’s not like it’s too short. I going to look deeper at the cutoff lever because all signs seem to be pointing to it. It kinda looked like it wasn’t sittibg fully forward which could have something to do with it.

Nuclear option is looking really nice right now

Nathan.g May 1st, 2019 11:35

Closing the loop on this - I went nuclear. bTC MK2s were on sale at TA so I picked up 2 of them rather than deal with this headache.

Thanks for the assistance!

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