Failing MK2A Graphic EQ investigation

[a.nonyme]

Hello forum,
I got an 1981-ish MK2A with a graphic EQ.
The EQ slide-pots for the 5-bands seem to work only when they're all the way up or all the way down but
not at the intermediate position: no tone difference whatsoever.
Is it the normal behaviour (I doubt it but worth asking ...) ? If not what could be the reason of such failure ? Dead slide-pot ? Capacitor ?
Thanks,
Seb

 

[dodger916]

It's not supposed to work that way. You could always call Mesa and ask for Mike Bendinelli, the Mesa in-house guru on Mark amps. Great fellow, and always very helpful.