Need a good reputation repair shop for Mitsubishi DA-P20 preamp.

I had originally posted this in “Vintage” topic and only received one response  that recommended I buy a newer preamp as technology surely would exceed this vintage piece and while I understand and appreciate that viewpoint I’d still like to see what it might cost and it also works well with my amplifier so thought I’d try in this topic…
 

Fellow Agoners, I’m looking for recommendations of a repair shop preferably Nevada(my state), CA or Western US for my vintage Mitsubishi DA-P20 preamp. When powering up the preamp the sound is broken up and varies drastically in volume. After it’s warm it works fine, however the time to warm up without the problem keeps getting longer. I have a local shop and have had them repair a vintage amplifier but they only seem to fix exactly what is broken(appreciate that) and won’t consider that a 1975 era preamp might need capacitors replaced or at least they won’t take on that rebuild  job. While I appreciate them not taking advantage of the repair situation I also don’t get a warm fuzzy about their repairs as the first repair they did had issues.

Suggestions from those that have actually used the repair shop they are recommending are greatly appreciated.