Ok, had a chance to look inside the head. All nuts are tight so not sure what is vibrating - nothing fixable by me anyway. I also left it and the warmup plugged in for 10 minutes and the buzzing didn't diminish. I am testing by plugging them in directly to wall outlet, not through a timer or the stabilizer.
I've had 2 other cold lights and they have always been completely silent no matter first turned on cold or when warm. I could sure do without the buzz when focusing and enlarging. Am I out of luck with this used cold light?
Thanks,
Mark