Marshall 1959T (year1969) problem Ghost Notes

[binito]

saw the ghost notes occur when the voltage on the screens fall of 490V to 420V (full volume )
It may be that the BY127 diodes (only 0.5A each ) Part of the Problem?. If Changed by IN4007 ?

[Jazz P Bass]

Neither the BY127 nor the 1N4007 have a high enough voltage rating.
(Personally, I do not like series diodes)

Peavey uses the SR2873, rated at 2000 volts.

You can try the amp without them installed if you think that is the problem.