I think I figured out why the blake was jamming; it's because I didn't have a rope bridge. When you use the D rings on the leg straps, after a pull, the standing end has a tendency to elevate a few inches above the running end, which causes the micro pulley to maintain constant pressure against the hitch before and after the pull. When I attached a rope bridge (really a quick link), the standing and running end of the saddle maintained alignment which caused the micro pulley to drop an inch or two after a pull. That inch or two drop apparently gives the hitch enough breathing room to not jam.