Retrieving item that slipped behind the back bed tray

Remove that back storage unit:
1. Remove the 7 screws holding it in place.
2.  Lay on your back, reach above your head & grab the two cross brace pieces of wood inside, then lift it out.  If you're lucky, it will be sitting next to the heating convectors.  Otherwise, it's under the thin plywood piece on which the convectors are mounted.  I haven't had to go beyond that point so far.  I did drop a small object below there once, but it was metal & I got it with a magnetic grabber on an antenna-like extension.

Here’s my fix to keep that from happening. So far, so good