Intermittent issue in old Vibrolux Reverb

[Diverted]

A friend of mine has given me his amp several times to take a look at. He said it was distorted on certain notes, but it comes and goes. Original 60s Vibroluix Reverb. It's been recapped (power supply filters, bias cap and preamp cathode bypass caps).
I had it twice and never heard or could reproduce the sound, and I didn't have audio clips so I was hunting blind. I did the usual ... checked voltages, solder joints, looked for leakage (on the coupling caps between PI and outputs... I could never find anything wrong with it.
I just got an audio/video clip of it happening again. I haven't gotten the amp yet but will soon I think. What's this sound like to you? I haven't heard this exact issue before. Thanks.

https://imgur.com/a/JWGN9mn

[Dave]

Sounds like a preamp tube only making intermittent contact in its socket to me.


Dave

[rafe]

Has He tried other Guitars??