D-15 Series 2 skipping

Now the bad parts. He said the tractor had set in the toolshed for years. The battery was dead, so it never got started. He said it hadn't been started for 4 years. I think it may have been more. When they decided to sell it, they put a new battery in it and tried to start it but couldn't get any spark. (Several of you remember my post on the frustration of getting spark.) I paid, what I consider, too much for the tractor (especially with this problem)!

When I finally got spark, I had to rebuild the carburetor. When I got that done, it started right up but had a skip. I tried different plugs and wires and realized that cylinders 2 and 3 were the ones that were the problem. 

Finally, I ran a compression check (per DrAllis directions - WOT, fully charged battery and a battery charger on while doing the compression check). I got about 160 psi on both #1 and #4 cylinders, but low 60's on #2 and #3. My initial thought was that the rings are frozen to the piston on #2 and #3, so I removed all the plugs and hand squirted some ATF fluid in the cylinders. I let it sit for about 3 weeks and intermittently turned the engine slightly (by the belt pulley). Yesterday, I put some paper towels in the sparkplug holes and turned it over with the starter (to blow the oil out), then replaced the plugs and started it. HOLY SMOKE!

Unfortunately, it was still skipping and after about an hour of running, a compression check revealed practically the same readings as before.

Am I on the right tract, thinking the rings are stuck to the pistons? Is it possible the head gasket is bad between #2 AND #3 (engine does not overheat or have any steam from exhaust)? Any other thoughts or advice?

I should have put in the post that I did take the valve cover off, checked the valve lash and all valves seem to be working as they should.

I will pull the valve cover off again and turn the engine by hand and watch each individual valve. 

By the way Doc, I don't have "a good tech" - just me!