Help please: Static from right channel GFA-555ii

I have a low volume, static sound coming from the right tweeter. I narrowed it down
to the right output of the amp through usual troubleshooting methods.

It doesn't exist when i first turn on the amp, it takes about 15-30 minutes 
before it can he heard. Once it kicks in, Its always there, but its more apparent  on the quieter passages...meaning vocals without a band, or just a guitar.

I live in NYC but its still hard to know how to get this fixed...its a 20+ yr old amp, but i do love the sound.

Marantz CD67II
Aerial 5
Does anyone know of a reliable Adcom repair service in New York City?

Stereo Exchange did a good job with my Aragon 18K when it needed a tune up (dirty contacts) last year. I think they chraged ~$100 to check out the problem and if they can fix it in 1 hr, then that's all you pay.  
Thanks for the tip. It wont be easy to haul the amp to them from upper Manhattan, but its good to know they do quality repairs. And that will give me an hour of listening to equipment i couldnt afford in 10 lifetimes :)