Hello fellow 650 enthusiasts. What may be simple question... any suggestions as to how to remove the oil strainer cover on the bottom of the engine? After removing the six (6) bolts from the cover it does not want to come off. This is a 1972 Yamaha XS650 (XS2). I don't know the history of the bike, but it may have either been a long time before it has been removed or possibly never. See diagram below. I haven't tried heat yet, but that is likely my next step unless someone has a better idea. I don't want to damage the cover. Perhaps some persuasion with a rubber mallet? Thanks and Merry Christmas!