Ev1 has been right on so far Michelle and if you get to the point of last resort with the engine you have leave the oil in it add about 1 quart of kerosene to the engine run the engine for about 5 min at normal idle. Possibly over the years PO had used detergent and non detergent oils in the motor. As long as you have plenty of oil in the engine the engine shouldnt seize within the 5 min run period. Then drain your oil clean the oil bath out real good and try again. If it improves try the same sequence one more time it sounds like you just have sludge build up blocking the passages. hope this helps some.
Alan
