King Arms ver 3 mechbox shell. IT's KILLING ME!!!!

[Schwag]

Hi.

All last night, the simplest job broke my brain.

I am replacing the mech shell for a guy. Ver 3. An easy job right?
For some reason the gears and piston are too tight to move together.
The gears move fine with no piston but when the piston travels along the gears, it locks up. It's like the hole for the bushing was set too high and the gear teeth can't clear the teeth on the piston.

Has anyone used a king arms shell before? Are they problematic?

This job had been a joke from day one.
The first replacement shell came from deepfire. Worthless piece of 3rd rate shit.
Returned it and got the king arms with the 7mm bearings pre-pressed in to the box.
Then the piston had too much wear. Ordered new piston.
Now even though all the parts are in perfect order, the gears won't draw the piston back.
This should be easy but I have spent 5 hours trying to get a simple mech box to work and I have had no luck. ARGH!

If you have any suggestions, please let me know.'

Cheers, Jay

[Skruface]

Try carefully sanding a mm off all the teeth to make them shorter. Might help the piston clear the gear teeth without binding. Alternately, also try sanding the rails on the piston with very fine sandpaper - maybe the rails are too fat and binding in the grooves in the mechbox? Polishing the piston grooves on the mechbox wouldn't hurt, either.