Z3 Roadster (E36/7) Z3 sub-frame question

Nine months ago I purchased a 1997 2.8 Z3 with 23k on the clock, had a PPI performed and no real issues found, in addition the rear sub-frame was in great shape. I want to keep an eye on this issue so I have two questions; first, how often does this problem occur, this car is for enjoying that top down experience; Blue Ridge Parkway is in backyard, “I am very gentle on this vehicle.” Second, how do I get the tool box/ holder out of trunk to inspect the floor?
Thanks
LGM:

Based on the above, your car isn't a likely candidate. The tool tray can be lifted up without removing it completely; just remove a couple of plastic nuts. The handle/cable for the spare will prevent complete removal, unless you unscrew the base of the cable (there's a *hex* to put a wrench on) from the stud coming up from the spare tire carrier.

I took my tray completely out using a dremel to the thin plastic under the big washer/nut so the handle would fit thru and be covered by the washer when I put it back in. I tried to soak the hex but no give so out came the dremel.