Gasket removal. Discovered that gasket remover does a great job of getting stubborn varnish out of internal areas that are hard to get at. Crankshaft cleaning / minor polishing. Flushed all the crankcase oil passages thoroughly with solvent. Note that in first crankshaft pic the first two throws have very mild surface corrosion. In second picture it is gone -- just a bit of light rubbing with Scotch-Brite 7447.