Peavey 5150 volume spikes !

[Rufio310]

So I was recording and me and everyone noticed the volume started spiking out of no where . The volume kept spiking up and down . We were thinking it was the tubes ?

[J M Fahey]

Why the poor tubes.
I would rather suspect bad contacts (*lots* of jacks/pots/switches/card connectores/etc.) along the sound path.
Or even external equipment (pedals, cables, even the guitar itself)
Try to reproduce the defect and only then try to separate, at least in wide areas, where you lose signal.