Tina Wood at The Amp Shop in North Hollywood.
I've been taking my stuff to her since 1994 with nothing but great results. AND... I did some work there with the owner recently and saw her clients come&go completely satisfied for the last 1.5 years. (& LOTs of them are big name cats too) She's always busy, so allow about a 10day turnaround, unless you want to pay rush fee, but she's very well worth it and very reasonably priced. (tell her "G" sent you!)