Not sure if anybody else has had this issue but I have had issues with the Diff in the Rear of my G4RS 09.
The issue I found was due to the Belt Tensioners being around the wrong way... now what I mean by that is that each Orange belt tensioner has a very mild notched mark in it at the top side which is marked inside the "serated circle"... initially I set these at the top of the Diff which then rubbed on the actually chasis plate... when I reversed it so that they are now both at the bottom the Diff freed up and now spins beautifully.
I have highlighted them as they appear in the manual below. These must sit at the bottom of the Diff Bulkhead 504057.
Hope this helps folks with assembly.
