Although now in the coin business while still selling some audio parts, John Peterson, going by the username soundvalves is still active on Ebay. If you contact through the Ebay email system I believe there is still repair capability.
Otherwise, any skilled tube amp repair service should be able to help you.
My own gold-faced VTA-70i amp sounds great although the matching VTP-101i preamp is faced in Henry Ford black.
Do you have any preamp booklet or schematic? I have only the assembly-instruction booklet for the amp.