McCormack DNA-1 Protect Mode light glows dimly

I have a McCormack DNA-1 that I purchased new in 1992 (IIRC). It has been in storage for a while, but I took it out today and hooked it up to a pair of new-to-me PSB Stratus Golds. The front end was an old Marantz receiver using the Main Out taps and a 1987 vintage Sony CD player. The sound was INCREDIBLE!!! However, after an hour or so at reasonable volume (since I live in a condo)(1/4 turn of the voume knob)the amp cut out and the red light of death appeared. I removed the top and inspected all five fuses (4 inside plus the main power fuse) and all are good. I let the amp sit, then plugged it back into power only (no inputs, no outputs). Now, the red protect mode light does its usual glow for 20-30 seconds then fades out. But, it does not fade completely dark! It still glows dimly. What could this be an indicaton of? Is the amp safe to use?

Thanks in advance,

Bob Martin