Compression tester is not needed, you told us very early on it would lift the front wheels off the ground without the blade carrier fitted. These motors will still run with very low compression. I have run these motors for many years with the decomp valve plugged without problems because the compression was so low but they cut the grass without issues. Remove the decomp valve and fit a spark plug and pull it over, you will find the compression is adequate for it to run. If you have spark the timing is correct because you can't alter it. You say you have spark, compression will be fine, only leaves one thing missing, fuel. The only other possible cause could be a leaking lower seal on the crank. Have you removed the inlet manifold and lost the seal
