Yes, if you've swapped/tested everything external to the amp (cables, cabinet, instrument, etc) and you know the problem is definitely in the amp then it's time to put it in the shop. Regular amp maintenance, like spraying contact cleaner in the pots, checking for burned components or broken solder joints, using compressed air to blow the dust out, can help extend the life of your amp. But yours sounds like a component failure that a tech should look at.
Please forgive my profound glimpse into the obvious.
Thank you for your indulgence,