I have bought repair parts on line and replaced heads, rods, valves. It depends on how much your time is worth. a few years ago my kids turned on the shop compressor when it was 22 * F and the rods did not get propper lubrication, I bought new rods, polished the crankshaft , I made my own rod dippers and X ed the rods and drilled oil holes. like when I rebuilt a Model T 4 Cyl engine. It's a bit noiser than when new but has been running the last 10 years, after setting 10 years before rebuild. I have a water pipe heater strip wrapped around the pump I plug in during the winter.