where to get a Rawson Aleph 5 clone repaired?

I just bought a couple of Rawson Aleph 5 clones on Audiogon.

One of the amps sounds great, the other one does not warm up.

Before I send them back to the seller (heavy) I wonder if anyone knows where in Southern California I could get a technician to take a look at it.

The circuits look simple enough, but all I got is a voltmeter.