The five main case screws on the back are made of soft steel and the heads strip and rust easily.  I found the
part numbers but I haven't been able to get any new ones.

screw 612-285 x 1
screw 622-205 x 4

The TO-220 final is NOT a MOSFET / BJT as it may appear, it's a custom-made IC just for this radio.
suitable replacements:
SRFH1900
MRF260
NTE342