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

 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 1975 amp might need capacitors replaced or at least they won’t take on that job. While I appreciate them not taking advantage of the repair situation I also don’t get a warm fuzzy about their repairs.

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