Sorry for the delay, I didn't get a notification for your replies (strange because I got them for the first ones).
Thank you Toni for the info on the biasing procedure
Anyway, I bought the new caps, 100v 22000µF Nippon Chemi-con with exactly the same dimensions except for a little less high. I will place something underneath them to get them to the right height.
Is there something I should absolutely check before turning on the amp with the new caps, waht they call the "monistor" for example, or the triac ? Are those prone to failure ? I ask this because when I first turned on the amp without the dim bulb the circuit breaker was "cracking like hell before stabilizing after a few seconds and well next of course the cap blew so... (again voltage across the cap was 76V.
Also I noticed the thermal sensor that is in parallel with one of the resistors in the fan circuit is reading open circuit, which means I guess that the fan is always going to be in the high position right ?