Amazing isn't it. I've had first hand experience with a set of engines with a combination of problems.....i.e. completely blown seals, bad rings, and bad crank bearings. The engines still turned up 5,400 despite these problems. Of course they had no torque whatsoever. Maybe this is why the previous owner couldn't seem to get airborne while taking off downwind and rolled it up into a ball. He blamed it on the engines.
George tells me Reg rebuilt 686's engines at some point. I'd imagine they haven't seen a wrench since then. I'd be real suspect that these engines have been run with the wrong ratio at some point if compression is this low. A simple ring job may or may not be the solution.
Mark, sticky rings are almost always a function of rich ratio. More than likely a new set of rings and quick decarbon will get the engines back in shape.
S