NMRCDude, if any, how much do you have the shaft shimmed between the spur gear adapter and motor mount? Too many shims will bind the drivetrain and make it click. Also try loosing the 2 screws on the front and rear of the diff covers, what are the sizes of those screws? They should be, wait let me get my manual........3X8mm. Any thing longer I'm sure will start binding the bearings, also try swapping the diff covers front and rear.