when you have an hour to waste
power off, unplug
vacuum out any dust, one at a time CAREFULLY unplug ever cable then plug back in. reseating cures many problems
if you aren't afraid of a project, take boards out 1 at a time, clean bottom of board with 91% isopropyl and a tooth brush
look for a "ringed" solder connection that might need to be resoldered
View attachment 178426
the first part will probably fix your problem