Nice approach Wilko :) I will apply deoxit on dip switch to ensure function.
If it's a clue, it's been a while since I reached this same point in the service manual (by the way, I haven't had time to pull that thread yet, I'll tell you the results) because although input 1 (0.5 to 18 GHz) worked fine, it never passed the [SHIFT] + [1] test. The 75000000 never appeared on the display, but since the device counted, I continued using it. If that check tests the internal oscillators and there was never a correct signal, how has it worked for years?
It is a mistery...
RubenRubio