HD One-Fifty Head Tone Control latency

hey folks,
i'm getting an HD-150 Head. it's the version without any effects like reverb or trem. just a the plain 150 watts 6L6 based tube Head.
the seller stated some issues revolving around the tone controles that appear to have a latency on the. in other words: when you dial in some mids or treble it will take a while to take effect.
is anyone here familiar with this problem?
i guess the caps in the tone stack are faulty? or could it be a more serious issue involving the ICs or something? can they be easily swaped out?
greets,
-rob.

I'd try cleaning those pots first but THAT'S a new one on me. I suppose it could be cap that's flaky until it warms up from internal heat. Possible. That's probably one that you'll have to follow through before and after it changes with a scope.

thanks for the reply mike!
ok, the seller did some more testing for me and confirmed that there is actually NO change in sound when turning the bass and mid pots. not even after a while.
the amp is pretty old. could it just be some faulty pots or caps in the tone control circuit?
can anyone decypher the sn. for me?
AO05053

AO05053
small size=A
O=130/150 watts
05053+number of series this is the 5053rd amp in that series