Well, I bought the leakdown tester but never had to use it... I went out the other day to move the car and it mysteriously started to run better after I started it and it warmed up a little.. checked the compression on the cylinder that got 25# and it was getting 125# and it was firing, which to me said it was a sticky valve because that is the only thing that could fix itself but... after it cooled off, it stuck again. My dad told me not to do anything to it and to change the spark plugs w/ 1 step hotter and see if it ran better and just to stick to that plan, as was what he told me to do before I diagnosed a low compression issue.. he came down and I still hadn't changed the plugs ( they were burning true and looked perfect, except #5 the dropped cylinder ) cause I saw no point, it was not the problem.. well we changed the plugs, and it did nothing, no supprises to me there. then we were changing condensor and points, coil, plug wire, trying an electric fuel pump ect... I tried to tell him it was a valve issue and he wouldn't listen... finally after he did a power balance test by pulling plug wires, he determined #5 was dead.. after verafing it had ignition, he pulled the valve cover and just as I said, a valve issue. the valve stuck open and let the push rod fall out of the rocker.. put it back togther, turned it over and it stuck again and did the same thing, so he put it back togther, I turned it over whail he held the rocker down, it broke loose quickly and now runs great again.