First off, I admit to being on my third set of tubes with the PrimaLuna integrated, but to me tube replacement for tube gear is the equivalent of getting an oil change or new sparkplugs/brake pads for your automobile.
On the tranny side, I've had trouble with two NAD integrated amps (one a 3020, the other a larger model I can't remember which). A Transistronics preamp. A Marantz integrated (I can't remember which). A Moon phono stage (I can't remember the model). Sorry I can't be more specific here, but memories of failed stereo gear thankfully fade into the past for me. Finally, yes it might have been a mechanical problem and not a transistor problem, but I also went through a Marantz CD/SACD player that, one day, just decided to stop playing one of the formats.
I must also say that I'm not including noisy volume controls or switches that I could easily quiet with a dose of Deoxit.