Ran across this post as my 20177 Laramie passenger side mirror is intermittent in folding. As I was reading through the Gruven website information on the replacement gear, it has this caveat posted in the DIY section for folks just wanting to replace the gear vice replacing the entire motor unit:
"** You Must Use the GruvenParts.com replacement motors when using this brass gear. This
is because the OEM motor sends current through the motor case, which isn’t an issue with
the plastic spur gear. However, when using the brass spur gear, the current path could
proceed to ground. Our motors do not use the motor case for the ground and therefore must
be used with the brass spur gear"
Just thought I would through this out there in case folks might be inclined to use the replacement brass gear in the OEM system.... YMMV...