Sorry - it took me a little while to get back to this thread.
Check your cylinders with a compression tester. Sears sells them for under $30. Get one that has the screw in fitting for the spark plug hole. Switch off, gas off, throttle WFO, and use the kick starter. You're looking for compression over 100 PSI as your minimum. 115 - 125 is good. All three cylinders should be no more than 5-10 PSI different.
Use the 6PSI pressure test for your crank seals. Sorry I described more how to build your test equipment and really didn't cover how to perform the test! Pull the spark plug on the cylinder you want to test. Seal the intake and exhaust ports as described above. Rotate the engine until the piston is below the transfer ports. It doesn't have to be exactly BDC but the upper transfers should be clear. Slowly pressurize the cylinder with your basketball pump until you get to 5-6 PSI. Watch the gauge and see if it will hold that 5-6 PSI for about 6 minutes. Usually it's really obvious if your crank seals are bad as you won't be able to pressurize the cylinder in the first place. Sometimes you have a seal on the edge and the pressure test is the last straw for the seal. This is actually better than having it fail while running though.
If you need the crank rebuilt, I can recommend several rebuilders that are good. It will cost you about $150 to $200 and you'll need to buy all the required seals for the rebuilder. Plus it's good to replace the big end rod bearings and thrust washers while you are at it....
Hope this helps!