I know that when I owned the Audio Aero Prestige, the manual suggested that I leave it "on", and with the "no disc" message when not in use. When I bought a Steelhead, and no longer needed the pre function of the Prestige, I went to a Cary Pro.
Having had a first gen 306 a few years ago, I knew that the SACD function (Sony, I'm pretty sure) was touchy; so I used the Audio Aero's recommendation on the Cary (Pro), and never turned it off either.
I know the Modwright is a tube rectified player (once upgraded); but those are some long hour tubes.
My question is: When you got it to work the last time, and then it worked for an hour and then went out again, was it after being shut down and then turned on again? My problems with the early 306 were never during play; but only when re-booting the player. Occasionally I had to re-re-boot; but it was always just the right channel that wasn't playing.
I would try turning it off and on; re-plugging it again and again, to see if I could get a good read. If I got one? I'd keep it.
This is one of those postings that I'm pretty confident won't help; but on the outside chance that it might, I'll put it up.
Good luck!