I have had one that the valves were just a little to tight and it would not crank for crap. One thing that was not mentioned, if your valves are way to tight then you are not going to get a good reading on compresion until you reset them. I would reset my valves first and then check compresion. Let us know what you find (If your luck is like mine you won't want to tell anyone what you find due to it being something you did) Good luck.