High mid slider on GEQ isn't working

So I've always just thought that the high mid slider didn't have a significant effect on the tone compared to the other ones, but I realized the other day that it's just not working at all. I figured it out by lowering them all down completely, then raising them all up one by one, and sure enough, that one slider has no effect on the tone or volume at all.

So my question is, does this most likely mean that the default high mid level is now neutral (center position), or is it possible that it has been stuck at the maximum or minimum GEQ level? It does seem to have alot of high mids, but it could just be the naturally aggressive mids of the Mark series. How much would something like this cost to fix, and do you think it's worth it to get that extra slight change is high mids? :?

get it fixed....you are missing more than you think by having one non-functional EQ slider.

that said, i had a dead middle slider on my IIB when i bought it ($1200 for a 100/EQ/Rev/Hardwood 1x12 w/JBL K120). i have a few years of of amp repair/restoration/building experience so it wasn't a big deal to repair mine (and do a cap job and bias adjustment while I had it open). if you have no repair experience, find a tech you trust and have it fixed. a fully functional onboard 5-band EQ on your Mark III is a powerful thing.

get it fixed.

I have a problem with my Mark IV. Got it used, Lead Channels 3-channel eq controls dont work properly. I havent sent it anywhere yet for fear of it being gone a long time and costing too much. that, and I have a back up amp for gigs but it needs a terrible retubing.

I have the same Problem with my Mark IV.. The lower mids slider is dead.
I just opened the Amp but its not possible to get the EQ section out of it if you don't remove other parts of it.

Edit: Finally i found the problem.. and now I'm trying to fix it