One quick way to find a bent pushrod involves watching the engine at idle with the valve cover off. A straight pushrod will spin at random. A bent one will stay in the same position with little or no rotary motion. It's almost impossible to eyeball a pushrod and see if it's bent, unless it's rainbow-shaped from a badly stuck valve. Another checking technique would be to remove all the pushrods and roll them over a completely flat surface like a sheet of plate glass.
My favorite method of freeing up sticky piston rings is to run the engine at a fast idle for 15-20 minutes with a fresh fill of cheap 30 weight oil and a couple of quarts of Diesel fuel added to severely over fill the crankcase. The crankshaft counterweights splashing into the oil/solvent mix will scrub the crankcase, pistons, and rings like they were in a washing machine. DO NOT drive the vehicle or put any load on the engine while the Diesel fuel is in there. Drain the stuff out while the engine is still hot, change the filter, and refill the engine with oil. I like 15W-40, but opinions on oil are like "noses"- - - -everybody's got one, and some are pretty smelly!
Jerry
