[Dave]

That's an odd one, it seems like the plate is there as a noise shield. Another thing to consider... has anything been moved around (wires or components) or has the length of any leads changed? Even a small change can make a big difference. I noticed something else in you pictures that could be an issue in the future. The exposed leads of the electrolytic that's strapped to the chassis look like they could easily short if the radio gets jostled around. You may want to dress those a little shorter or cover them with some heat shrink.