I've got an '86 240 wagon with some brake issues I need to figure out. On seperate occasions, months apart, my left front and right rear calipers have each briefly failed to release fully, keeping enough pressure on the rotor to overheat the pads and make them stink. In the latter instance, with the rear caliper, the pedal got noticably softer during the overheat, though the car continued to stop. In both instances the problem seemed to fix itself, coming unstuck and cooling off with no extra effort on my part except for a few minutes of driving. The car doesn't get driven much -- maybe 7k miles a year, often sitting undriven for several days. Does this sound like warning signs of full-fledged caliper failure calling for replacement, or is there some less drastic explanation I should consider such as corrosion around the pads? Is there some test I can do to clarify the apparently marginal situation?