I assume it's located under the carpet panel in the engine bay. Looks easy enough to remove.
Yes, what we call the quarter-window panels.
The belt reel and retractor are housed in a plastic housing that is
supposed to prevent engine bay fumes from entering the interior. rotfl
The plastic edges warp on the housing, and the fumes (or Lotus Perfume as we say) enter the interior.
Lotus lined the plastic housings with headliner material, yes the same stuff that disintegrates on the headliner. IMAGINE just how long it lasts in the heat of the engine bay...
When I had my gas tanks out I addressed these issues. You can see the reel on the left side of the first picture (cover removed).
I removed the headliner material (actually, it just fell out

) and lined it with DynaMat (car audio sound deadener). (Second picture) I added a seal around the perimeter (bulkhead mating surface) as well, before I bolted the housings back on.