On my Peavey Valveking 100 head? The 1 input has to be jiggled A LOT to work. I have fixed this on guitars. But never a tube head. Any help?

1994 MIM Squier Strat with custom paint
Agile 3000

Peavey Valveking 100
Marshall Lead 1960
Marshall JCM 900 SLX
Carvin 4x12

Zoom G7.1ut
get some bubble gum or take it to an amp tech its an easy fix
Peavey 6505 120W Head
Ibanez Rga32 (FOR SALE)
Laney Lv412a Cab(FOR SALE)
Soon To Get::
Boss DD20
Morley Bad Horsie II