[morzh]

David


You don't want to swap the parts. If this is, say, a switch, it will take as much effort as building a whole new chassis from scratch. Exaggerating. Still pretty bad.

Clean the switch, clean the switch, clean the switch.......


then:

1) have you measured the voltages yet? If not do!.
2) In particular, if after the switch cleaninig the problem persists, see if the voltage is present on XXL (the very first) tube plate.
3) If the voltage is OK (well, typical plate voltage, not units of volts or a fraction thereof), check the continuity of both coils in the RF xfmr 35 (the plate winding will be OK).