Hello Klaus
Thanks for you r answer.
I´ve already tested this capsule in another U67 so, the capsule is ok.
This are my voltage readings with the tube in the socket:

All the PSU readings were correct
Plate voltage is around 89V (a bit high than in schematics)
Knot R14 and R15 = 220V - OK
Knot R13 and R12 = 2V - Not OK (should have 59V)
Capsule pin 1 = 2V - Not OK (Should have 59V)
Capsule pin 5 = 6V - Not OK

So this might be the problem...

Do you guys have any report about any faulty capacitor or resistor that might cause this voltage drop?

Thanks again for your help

Mário