Current engine is now past TBO at 2150 hrs. Just came out of annual 2 months ago with compressions at 76/78/78/78 and no sign of engine wear in 50 hour oil changes. The engine has had a minor oil leak that is presumed to be at the back bottom of the crankcase (from dye test) since I purchased it (didn't show up on pre-buy). Nothing on the floor, just a small amount that gets blown around the engine compartment and ends up accumulating on nose gear doors and belly over time. Other A&P's tried addressing it without success. Can't be addressed without pulling engine and even then, no guarantee it can without resurfacing case halves. So since the engine is past TBO, also needs new engine mounts and some new hoses. Seems like the time to get it all done.
I guess it's possible to pull the engine, try to fix the leak, reinstall with new mounts and hoses, but if that doesn't fix the leak, I'm out $$$ with an engine that is still past TBO.
Also, a Turbo Normalizer was installed in 08 (1200hrs) from M20TurboKits out of FL which doesn't appear to be in business any longer. But they used a Rotomaster turbo and scavange pump and Rotomaster is here in PHX area so I'm going to check into getting that rebuilt.
That's about all I can think of. If it weren't for the oil leak, needing new mounts, and hoses, mechanic thinks she'd be good for a few hundred more hours.