Well, been my experience that the unloading auger, reel lift, and header lift are all tied in together in the same string of valves. The header lift is primary....unloading auger secondary....and the reel lift is final. So with that said.....that is a closed center system and I'm beginning to wonder if the valve that stays closed till pressure is needed has broken a spring or the ball detent is gone or something along those lines and the pump is running full bore and you are hearing your bypass screaming it's tail off. Where is the pump on the 7720IJ My 6620's was under the seat and the 8820 was over by the radiator in the engine compartment. If it's under the seat perhaps part of your vibration is coming from that shaking and hammering......I don't know. I'm tossing ideas here is all as I've never dealt with this before but I would tear that pump down or put your hand on it. Run the combine for say 10 minutes and don't touch a single hydralic function....if that pump is hotter than hades than it's just circulating fluid and something went to crap on you inside of the pump. In a nutshell....it sounds like your pump has internal problems. Should be able to test it on the machine somehow but I don't know for certain.....Deere tech could fill you in on that. lIke I said....I don't know for certain.....just trying to toss you some ideas that maybe you didn't think of If you find it be sure and tell us......You have my curiousity up now as to what's going on.