I just stumbled across an interesting troubleshooting idea.
Using a handheld infrared thermometer to check to be sure components aren't heating up over their temp ratings.
Surprisingly, these things are now sold as a cooking aid so ones with +/- 1 degree specs can be had for $30.
So, if something is smelling a little overcooked you can scan the components in that general area and look for ones that are 150 F or more.
I haven't tried this yet but this sounds like the kind of gadget that might come in handy.