got my brand new acr today and it was working perfectly except for a weird noise, took it apart all the way to the gearbox and the gearbox it self, lubed it up and closed it back up.
assembled the blaster and chucked a battery in it.
It does not fire now, a low hum emanated from it and it does not fire, battery wires also get hot quickly. I’ve tried reversing the polarity of the motor but it’s the same each way.
please help me, this is my first gen 9 gearbox
Grinding noise? Or?
Have ypu tried to run the motor out side the blaster? If no take it out and connect the wires see if it still spin.
If it does its a gearbox related issue I guess, something might be jammed for what ever reason
Yeah, I’ve already ran the motor outside of the grip and it’s fine. The noise is more of a hum, no grinding, the motor is just not being allowed to turn by something, one thinking anti reverse latch or tappet
try take the cylinder / piston assembly out, leave just the gears inside and spin them by hand,
see if it spins i suppose 
hope you get it sorted out soon man 
but if it was making that low hum noise from day one, it is possible the motor they put in was defective from factory, and eventually cooked itself and now doesn’t have enough power to turn anything…
Motor works fine 
thanks for the help man. I’m pulling it apart now, looks like it may be the piston or tapet. Again. I apprciate the help
Just to inform anyone looking at this thread, when I put the gearbox back together I didn’t set the gears correctly so that the piston would be free of the gear teeth when it reaches its back position. Instead the gears stayed on the piston and couldn’t move backwards
I took the gear box apart and reset the gears in the correct rotation qnd now it’s all fixed! But it was a lesson well learned, I don’t think I’ll make that mistake again hahah
That’s it
We all learn from our mistakes
so what was the actual issue O_o?
The gear rotation. When I initially assembled it, I didn’t put the gear that interfaces with the plunger in the right rotation and that stopped the plunger from moving forward after it had moved back.
Good to hear. I always reassemble with the sector gear teeth rotated where no teeth are touching the piston ladder.
I had never taken a gearbox apart so I didn’t know haha, I know now though lol