Here is the progress so far on the heel drop regimen (3 sets of heel drops on each leg, straight leg, bent leg, done twice daily).
In much of the rehab work between weeks 4 and 9, the heel drops I was doing were done on a flat surface so that the heel could not drop below horizontal. This was primarily due to inclement weather; cold, and late work hours; - I did the exercises indoors where I have a 1-step rise (for the lift leg). I started doing the full heel drops on a stair case outside more frequently during week 9 and started experiencing morning-after soreness in the achilles. Uh-oh. Reflecting on this I see that the weight progression done was mostly with the heel drops to horizontal and when I switched to the hanging heel drops the muscles and tendon were not adapted to it. So I've backed off on the weight. I have also started regular 4 mile walks. Both achilles are a bit irritated but particularly the right. They do not hurt walking (or running) but are tender when pinched, more so on the lateral side of each tendon.