Well, the vibration/lock-up problem still exists. Yesterday the
following was replaced:
brake line (just within, not the entire line from the master cylinder)
One thing I did find out is that the right axle has a repair
bearing. I'm not sure if this is of any significance since I notice no
vibration at any speed. Something else to note: the wheel that is
locking up is at least 40 degrees hotter than the driver's side/rear wheel
(this was acutally measured btw). It's not clear if this is just due to
the brake problem or a (possible) bearing problem (i.e. is the heat the
result or the cause).
At this point I can only come up with three wild guesses:
1) The repair bearing is bad in some way, causing friction, and therefore
a heat build-up. Eventually the brake starts to have a problem.
2) The pressure is still building up in the right/rear brake, causing a
heat build-up and eventually the lock-up problem.
3) Both #1 and #2 where one problem is making the other problem more acute.
As always, theories are welcome...