I've have restored a few Swans in recent years. The biggest issues were with the electrolytics (don't forget the hard shell ones, like the one on the PTT line), mine was shorted and I almost destroyed my finals on first test, luckily I was paying attention to the ammeter on the Variac supply. Definitely check the bandswitches-- clean them multiple times, and inspect them closely for actual contact (make sure you see the little fingers move). Other issues were with driving where the high wattage resistors (any of the big ones) had drifted *significantly* (10-100x) high. Checking all the Jones plugs is a good thing. Don't forget one ones on the power supply. Check out all your voltages, including the filament voltage. Sounds like you have already done most of this. Just keep at it. Swans sound fantastic when all is working well.