Sounds to me that the teeth on sector gear and piston doesn't like eachother, A.K.A there is too many teeth on the sector gear compared to piston.
Try putting piston and gears in and then start turning the bevel gear, if the gears stuck in the end instead turning the teethless half, you got a problem there.
Try putting piston and gears in and then start turning the bevel gear, if the gears stuck in the end instead turning the teethless half, you got a problem there.