CTW cylinder wear

Hi everyone!

Recently I've purchased the second hand CTW MX2. It was in the non-workable state, so after some repairs it came alive.
But the other issue appears - the sector gear could not grab the piston, only wearing the piston windows (from the forward side). Hopup is aligned well. What could it be?

the sector gear doesn't reach the piston teeth, so it doesn't pull the piston back?

if I understood correctly, then it's the first time I hear this; I can think at 2 reasons:
- ether the upper and lower doesn't align well,
- or the upper or lower (or both) is not machined well

you can try to add a couple of shims under the gearbox (one left and one right), between the gearbox and the lower, to rise it towards the cylinder, so it can grab the piston teeth..

What thickness of the shims should be? would 1mm should be enough?
Maybe it would be better to add shims under the screws, which holds the gearbox?

if not to take the motor into account, you would have to use exactly the missing distance from sector gear to piston teeth, but be careful, because the thicker the shims are, the greater the distance from the motor pinion gear to the gearbox bevel gear, so you may get the same problem there, or just not enough contact surface..

i think the problem is elsewhere though..

have you tested another cylinder, or your lower with another upper? if you can, do these tests, at least you'll find out where the problem is..

I think you should check the cylinder, it sounds exacly the same problem i had, i found out later on that i had broken my Piston, so everything was working exept for the piston/cylinder, the screw was loos inside the piston


regards

The piston is ok.
I've placed the shim inside it to prevent the wear from th spring tension.
Will try tomorrow to place some shims under the gearbox. The previous owner told me (and I believe him as I saw it) that the CTW works before.

Two ellips-like shims 1mm thick did the job.
Thank you everyone for the advices!

PS: also I've break in the motor in the distilled motor, on the 4.5V. I was impressed by the owerwhelming quantity of the dust there! The brushes still looks OK.