Well I posted a long reply but it didn't show up! I'll try again. As I said in first post, your compression is good. I think you have two problems. The oil in your air intake suggests to me that you have a blow head gasket but would not think the compression would be that high, assuming your gage is accurate. Blown head gasket is common on these and typically is between the cylinder and the push rod gallery on the underside, block side, of the gasket. My guess is that the noise you describe is from worn out bearings in the counter balance ass'y and/or worn eccentrics on the crankshaft that the counter balance ass'y runs on. These are part of the crankshaft and are not replaceable. Likewise, the bearings in the counter balance ass'y are not replaceable and the cost of both is prohibitive. This is usually caused by not changing oil often enough. Walt Conner

Did you check the engine oil before starting it after winter storage? Don't buy a new starter until you find out if you can turn the flywheel by hand! Check all cables, including the ground cable where it attaches to the frame, and clean up all cable connections and use new bolts in them! And, for Pete's sake--DON"T buy a new starter from a John Deere dealer!! They will charge twice the cost of one from somebody else! And, don't buy one, any way, it probably is something else. check the fuse in the fuse holder, near the starter solenoid. Its one of those new, flat type. Better take the battery to somebody and have them give it a load test. Gas stations usually have them. But not the gas and go type of place! You'd be lucky to find somebody there that would know what you meant if you asked. Some of the auto parts stores can do the checking for you, if you bring the battery to them. Those little tractor batteries are usually good for 2 summers. Because of the many starts they do, in normal usage. Can you get your car close enough to jump from it? (The current-not jump off it literally)

I would not go so far as to tell you "changing the Magnetron will eliminate the problem" even though I think it might. Evasive answer? Not so much that as I just would want to be absolutely certain that the engine was really losing all spark when it does not want to restart. And as has been pointed out in numerous threads (not this one), the only accurate way to really determine whether an ignition is REALLY making a spark (or not) is to test the high tension circuit while it is attached to the spark plug with the spark plug actually in place in the engine. To do this requires a spark tester that can be attached, and viewed by the testing person when the engine is running..........or cranking. The reason that simply using a spare spark plug and laying it on the engine where the gap can be seen is that an ignition system may throw a spark under atmospheric pressure but be unable to make a spark when the spark plug is inside the combustion chamber under compression pressure and in the presence of gasoline. If I KNEW that the ignition was unable to throw a spark when hot, then of course I could recommend replacing that Magnetron, but as they are sorta pricey, I don't want you to spend the money unless it is proven to be defective. Now, there is another thing you might do to see if this reluctance to restart when hot is carburetor related. You can pour a 1/2 gallon or so of cool water on the exterior surfaces of the carburetor and the intake manifold when it does not want to restart. This will reduce the temperature of the parts so the air/fuel mix entering the engine will not be so LEAN as to not support combustion. If this helps the engine restart, it implies that the engine may still be running a little warm. Also, there actually is a "hot starting" trick that I and some other members here have used with some success. This trick is to move the throttle to the wide open position, apply the choke fully but keep your finger on the choke control and as soon as you turn the key to START and the engine moves.............push the choke completely off. If none of these works then you may want to get a Briggs spark tester and check that Magnetron under real life conditions. This post was edited by mownie on Sat, Jul 13, 13 at 22:58

Only the solenoid post that has the battery cable attached will show voltage without the key switch turned to start. When the key switch is turned to start is when the solenoid post with the starter cable attached becomes energized. If the key switch you installed was only "similar" to the one you removed, and you aren't sure of the function of each terminal on both key switches, it's possible that you sent 12 volt DC power to the magneto under the top cover of the engine, and that never has a happy ending. If you had a way to post photos showing the terminals of both switches and the terminal labeling, and tell us which wires you had connected to each terminal, then we might be able to tell what happened. It might also help if we knew the model number of the Murray, sometimes you can find a wiring diagram for them still. Otherwise, "similar" ain't exact enough for me. I'm sorta similar to my wife in some respects (but very different where it counts).