power amp troubleshooting

Sorry, didn't know where else to put this, so hope its seen by somebody that can help me. I recently purchased a Citation 16A power amp off ebay in almost perfect condition, and it sounds great. Only problem is I get a slight buzz out of the right channel (tweeter only). It doesn't bother me much since it's quiet enough to be unnoticeable when sitting across the room, even during quiet passages in music. Is there anything I can do to fix this? It seriously doesn't bother me, but I don't want it to become more serious and damage the amplifier permanently or my speakers. By the way, its definitely the amp and not the speakers. There's no buzz when using the built in amps on my H/K AVR 7200 (which is used as a preamp for the Citation) The speakers themselves were built within the last 8 months or so, Wayne J's Eros design, so they're fine as well. Anyways, thanks for any hlep guys.
Have you tried swapping the channels on your citation? connect right speaker to left channel, etc. to see if the buzz follows the speaker or stays with the right channel (thinking some amp speaker interaction)

Also swap the input leads for the same check - if the buzz moves it is in the preamp output.

It may be an oscillation of some sort - do you have access to a scope?

Is the buzz there with the amp inputs shorted?

EDIT: Caution, be sure to power down before swapping connections