Under what?
The belly or the tail?

Very easy. leave the bottom screws in (as I recall) and slide the tray forward after removal of side allan screws. Hardest part is the laying on your back to get the bottom screws loose. You wont have any difficulty.
Wait till you see the oily black mess behind that thing. Youll be amazed.

Straightforward on the SDR at least - use the parts fiche as a guide to what needs to be loosened/removed.