Dear Raymond bravo pour l'effort
0/ first get service manual, see w140, Artech had ( costless) printed reprod.
Now check every power supply V, ripple, and troubleshooting or adjust if out of specs.
Then exercise and clean every switch and control, specifically attention to the beam finder, and HV ( focus intensity astigmatism)
1/ shaft coupler is available as spare part,
2/ power 60..90W is about normal
"seems hot"....use thermocouple or IR temp gun ( not accurate) for transistors température
Finger touche can be misleading
3/ The old Fans often fail, or slow down, check fan and air filter for good airflow.
4/ recapping...agree, easy to spot visually inspection of all lytics and tant in PSU.
symptoms of dead lytics..Bus V out of spec, .leaking corrosion, Cap has High has high ESR, or low capacity, high 120 Hz ripple on bus.
enjoy
Jon