Last update. I have replaced a faulty fan, and even found that securing it on the outside of the rear of the unit gives better performance for cooling. I also replaced the power capacitors which were SO bad and dry that they rattled! I increased the voltage rating from 100Volts to 160 volts. Of course the caps were much bigger, and I had to mount them off the board and run 14 guage jumpers to them. It is just as well, because now they are not square up against the heat sinks. The unit is in service and runs quite cool. I am looking at the P300 that I own and think maybe new caps are in order there as well. I will acquire a service manual, allowing me to see what other things might be maintained.