I actually performed this surgery on my '87 300TD within
the last few months. The clock hadn't worked since I
purchased it a year prior.
Upon removal, I found that the single resistor on the
circuit board was burned up as well - ugly black carbon
and all. Digging out my handy multi-meter, it appeared
to be about 150ohms (could not read the color bands on
it - they were ruined by the overheating.) One more trip
to Radidio Shack, and we were back in business.
Amazingly enough, after replacing both capcitors and the
resistor, the dang thing worked, and keeps perfect time.
I can't believe.
Total time start to finish, including coffee breaks, trips
to the 'Shack, explaining to my wife what we were doing,
etc. was about four hours.