thanks all. after all of that, the spring plates were both sitting about 2mm above the stop and weren't under any load. they will be when they go back on though. and thanks to a visit from no_h2o and his 17mm allen wrench, the whole rear is off now. fitting up the new stuff over the next week. a detailed tech article and pics to come.
now just to deal with the front adjusters (or lack there of).