I don't let anyone touch my gear. Maybe a base grind If absolutely necessary. "Don't touch the edges. Don't wax it."
I recently received a new board that was a blem and required some over the normal care. In addressing the blem, I neglected to take the base edge bevel to 1* and the board was soooo twitchy, I was disappointed it wouldn't work for me. Put it back on the bench and checked everything and put that 1* on the base and viola! The board rode amazing and predictable. Amazing how twitchy an "edge high" base will ride. I always tune myself and often. That way, you know what you have. You can buy a pawn shop board and practice practice practice. It makes sense to own the tools and know how to use them.