Anyone is far better off going into a shop having already nailed down the issue at hand. A technician responds to customers far better if they have done all the grunt work up front. Tech can then provide an accurate quote based on customer's troubleshooting, and will likely save money. It's human nature..you know, like the blonde who thinks its a good idea to buy a car alone, leaving herself to the wolves, but still leaves with a good deal! You can, I have been told, be taken advantage of financially if you don't show some semblance of intellect.
The shop that I utilize is nearly wholly supported through the Pro Audio customer base, whether it be whole house equipment, DJ stuff, or guitar amps. I can drop in with my gear, but need to be concise about what I want done. It is near impossible to find a shop that has a retail front. Both in my area are in industrial parks and are not necessarily friendly to walk-ins. I can hear that they get all kinds of inquiries about all kinds of equipment in all kinds of disrepair. Put your phone number out there and expect to field a bunch of calls about nothing, so if you call and are weak at understanding the issue, have an old piece of equipment out of warranty and are looking at a quick turnover for a good price.. well...you might get someone who is a bit snooty with you. Comes with the territory.
The majority of times with older equipment is that it simply needs the pots and switches flushed using DeoxIT or WD40 contact cleaner. The cost of trying it first (surely there is a YouTube video from a pro for edification) far outweighs even beginning the search to source a tech.

