Fri May 10, 2013 11:05 pm by Flazzbog
Take it apart and do it again.
You've probably borked up your shims. Adjust your motor height and if it still whines, take the shims off the top of the bevel gear and put them underneath so it sits higher off the motor piston. Don't do this all at once, do it progressively until your gun sounds good again.
Also make sure when you do it your gears spin freely and nicely when the mechbox is closed without the spring, but don't rattle around up and down too much.
Yes this is going to take forever.
Have fun tomorrow.