[Drake] Bringing a PS7 out of hibernation

[tav1 at vzw.blackberry.net]

Hi,
I want to put my Drake TR7A back on the air after being down for 15 years.
I know I should bring the voltage up on the PS7 gradually with a variac to reform the capacitors.  Is there any prescribed method for doing this, such as increasing the voltage by 5 volts for a certain period of time? If so, what period of time for each voltage increment? Perhaps I need to replace the caps?
Is there anything I need to do with the TR7 to bring it back?
Any advice is appreciated,
Torry
N3ANO