Audio Systems: Protection Light on on Yamaha Power Amps, output transistors, power amps

Question
I have a Yamaha M-70 and M-50 Power Amps, both units' protection lights come on when you turn them on. Is there a simple or likely solution to this problem. I would like to avoid the expense ofa repair shop if the problem involves an easy fix. Thank you for your expertise. I checked the fuses near the power switches and they are fine. There is a white fuse, (at least it looks like a fuse) that I removed and put back, but I can't tell from looking at it if it is in good order or not.

Answer
The white fuse is a ceramic fuse (fasst acting).  The problem is most likely shorted output transistors.  These are not the easiest beasts to work on.  The protect mode keeps the output section off to prevent further damage.  Both will need to see a service shop.
Dan