It's interesting that you were having issues too shipsupt. If we were both having problems then someone else probably is or will in time and information on the 717 is pretty hard to find so we should record what we did.
I started a thread about it which you can read here:
http://www.head-fi.org/t/665289/srm-717-trouble
So the exact trouble was that I'd turn my amp on and it would work fine until it heated up then it would cut out and I'd be able to hear the music faintly. The first thing I tested for was bias and offset drift. When this amp cuts out it drifts way off but that wasn't it.
After speaking with Kevin a bit over PM and in the thread he told me that there was no heat protection but there was a protection circuit that could be tripped. He seemed to think that the power supply was at fault and that the likely culprits were as follows:
Bad Solder joints
F1, F2 (.1a 250v fuse 6.3x30mm)
http://www.mouser.com/ProductDetail/Littelfuse/0312100HXP/?qs=sGAEpiMZZMtxU2g%2f1juGqbdCHRI5TALuk0WJ6P5yiFo%3d
C18,C19,C20,C21(220uf 400v capacitors)
http://www.mouser.com/ProductDetail/Panasonic-Electronic-Components/EET-HD2G471JJ/?qs=RjKrbPCWafn7m4DtwS9%252bFA==
R51,R52(1/2w 51ohm resistors)
http://www.mouser.com/ProductDetail/Ohmite/OF510JE/?qs=W5Ux/5YWIN4db%252bsBnvHI0Q==
R60,R61(1/2w 1m ohm resistors)
http://www.mouser.com/ProductDetail/Vishay-Dale/CMF601M0000FER6/?qs=/I5vA73T%252bYKqzu/rqtZOOw==
There were a number of dry joints on my 717. I was very surprised by this actually. Fixed that. No change. Then I did the large capacitors, the fuses, and R51,R52, no change. R51,R52 tested fine. R60,R61 are in a terrible place because their solder points are actually covered by the frame I had to actually unscrew the frame as you see shipsupt has done in his photos before I could get to these two. The whole unit becomes somewhat difficult to work on after you take the frame off because suddenly the back and the front of the unit are free floating as is the transformer and the main board. Anyway I took them out tested them and it turned out they were bad and they both tested high. Replaced them with new vishay metal film ones and voila! No more trouble.
For the future I understand that resistors can be tested in circuit in a limited way. If the resistor tests higher than it should while in circuit its bad. If it tests lower it will need to be tested outside the circuit or at least one lead will have to be removed from the circuit. This could help in determining which resistor has failed should you run into this issue.
So what did you do shipsupt and what was the problem?