Car: 1989 260E

I have a vacuum leak in what I assume is the diaphram that locks/unlocks the fuel door. All the door locks and the trunk lock work. There is hissing/leakage in the fuel door area when locking the car doors, but not when unlocking. The fuel door itself stays locked, and I have to manually pull the plunger to unlock it when refueling.

This seems like an easy fix, but the assembly is behind a piece of structural metal in the trunk. Before I amuse my neighbors by crawling upside-down into my trunk to get at it, is there an easier way to tackle this?

Also, a completely unrelated question:

Is it normal for the SRS light to stay on for a second or two after starting the car?

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2008 E350 4matic / Black/Anthracite

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Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black