Need some help. The gearbox is a king arms qc out of a 9mm pdw. The bearings are flat with the shell. The shell is not warped. I've tried 3 different 16:1 gearsets, and 3 brands of shims, and I can not get it quiet once the bevel gear is in the shell. No matter how high or low I shim the bevel just to clear the spur and spin, once I close the shell and rotate the gears with my finger, they spin many rotations but I hear a slight banging like something is catching. I've checked all clearances and everything checks out. The spur and sector are shimmed perfect and spin many times together, but once the bevel is placed in the gearbox, it turns to ****. I'm considering running the stock bevel as that has not gave me and issue. I have shimmed a dozen aegs without running into this issue. Yes I use bevel to pinion method. Any help is appreciated!