LSA Statement Amplifier Service Needed, Recommendations?

Everybody,
I purchased a secondhand LSA Statement Plus amplifier. It is exhibiting what sounds like ground hum.  I have tried all the usual ground hum remedies and finally brought it to another location in someone else’s system  to see if the noise was still there, and it was (albeit at a somewhat lower volume since my friend‘s speakers are substantially less sensitive than mine). I have been in touch with John Tucker of Exemplar who designed all the modifications on these units, and it’s looking like  he will not be available to work on the amp at this time. If you own one of these amps and it has needed service, would you please post any leads regarding competent technicians who know these amps and could troubleshoot one? I am willing to ship for service. Thank you!