software

The 2nd guitarist in my band has a Marshall 602 combo (60 watt 2x12, late 90's).
There is a problem with the volume going up and down.
I had taken it to a guitar/amp tech and he couldn't find what the problem could be, he said those amps have connectors that get dirty, but he wasn't sure, and not being a Authorized Marshall tech he couldn't get any info.
Can anyone help or recommend a Marshall repair shop?
I'm in the Chicago area.

Thanks,
Jeff

Go to the Korg website (Marshall USA distributors I think) and do a search for an authorized repair place. I'm sure you'll have no trouble finding one in Chicago.

Or just go to the Marshall website (might be easier) and look up service enters in your area.