Sounds like you need a "HV cup". If its like newer RCA
length is important here. Fix this first !
As for the tubes I would change all back to factory unless
RCA them self recomended the sub. 6GH8 were horrible
tubes anyways, we bought them by the gross. Keeping
origional will help avoid unneeded alignment. Its best to avoid
any adjusting of coils except convergence.
73 Zeno
