Your motor height AND bevel to pinion shimming is way way out.....
The motor height is never really guessed (only Mr Spock can make accurate guesses)
The motor height is checked and set in alignment with pinion to bevel
Then the bevel is shimmed to pinion once the motor height has already been determined & set
You should never need to tweak the motor height more than 1/2 turn either way
If you find that you need to wind it in/out a considerable bit then your motor height and/shimming you did was out
I don't think there is one single guide that explains it all or a straight forward 101% foolproof method
There is this that explains the motor height to bevel issue....
But you kinda have to feel what you think is best slight lash or a little tiny bit under shim on the bevel
Or the " walk " as Rogers calls it......
The motor height is set correctly, then bevel shimmed up against the pinion but not too tight/loose
If you search for Rogers " shut up gears " - spread over about 3 clips & measurement tools etc....
But jeez are they shimmed sweet....
I don't think I fully agree 101% with any video - balanced against what is realistic etc.....
But you should watch and fully understand the utmost importance of pinion to bevel & as close to perfection shimming
Get this bit out of whack and the whole gun is f*cked....
If over shimmed then as the pinion meshes fully it creates extra strain of bevel smashed against the bushing or gearbox
or if under shimmed the pinion keeps getting wound in further & further until the tip of pinion is rubbing on AR lugs of bevel
Normally....
AND this no way even a rough guide to even begin to go by as different bevels have teeth cut in deeper or shallower....
LOOK at the bevel in center....
its teeth are cut much higher than other two bevels on left/right so you can understand the shimming of bevel will not be same
So you can't just assume or take anything as a given oh about 0.25mm will do - coz it bloody won't
IF you had bushings in a G&G std box thenabout 0.20mm MIGHT do as a very rough guess
HOWEVER if you have used bearings then these sit much lower than bushings giving you more space to shim up on all gears
So this figure on top of bevel could be 0.40mm to 0.60mm
THIS ISN'T EVEN A WILD GUESS - I don't use bearings as a rule so can't even begin to guess
But I'd lay money it is much more than bushings would ever need
From what you say that the motor is wound in quite a lot then I'd take a stab that the bevel is undershimmed
By that the shimming on top of bevel is too little and your motor is far in to mesh and pinion rubbing on bevel AR lugs
(been there done that thinking yeah it spins ok - I have got this shimming malarky sussed - WRONG !!!!)
Watch first video, see bevel on one half of box, grip+motor fitted - set the height of motor and keep that setting
Try to gauge not guess the shims required on top of the bevel using whatever technique you feel is best
(there are loads of methods)
If you have to wind the motor in say a full turn or more you likely have under shimmed the bevel
If you have to wind the motor out say a full turn or more you likely have over shimmed the bevel
Your motor pinion to bevel should meet like the GOOD picture - max teeth meshing with a absolute whisper of walk
The moment you wind in/out the motor and they no longer mesh as effectively the energy is not being transmitted 101%
Resistance builds, heat/amps rise, fuses/mosfets blow and gun stalls - sounds familiar ????
99% sure your issue is shimming - mainly motor height pinion to bevel etc.....
There is also a very slight chance you can get similar issues if you have a very tight piston binding in the box
A new piston that binds a lot will slow the gun - even stall it in extreme cases
Rate of fire - even fps can be robbed in a slow returning piston
pistons can bind at the rear of box or in some cases a bad piston can bottom out
though in your case the gun is straining always so don't think piston is bottoming out on full retraction
It might be binding but tbh I doubt it with what other things you have said - 99% ya motor height/shimming is crap
Won't hurt to check piston for binding if you have ever replaced the stock piston at some point
But reckon you needto set motor height and reshim the bevel properly
Also do not shim the gears too tightly - if there isn't about 0.1mm to 0.15mm side play on all 3 gears you are shimming too tightly
Other issues like motor angle etc... if you changed pistol grip etc...but I reckon you need to set motor height
then quite possibly need to add a bit more on top of bevel
THIS IS A ROUGH - VERY ROUGH GUESS ONLY - YOU NEED TO CHECK STUFF YOURSELF !!!!
Hopefully you have or will soon understand exactly first hand where the shimming is out and where you need address the issue
Hope some of this crap helps, I've been there many times at first so feel your despair at your gun running poorly
