Now I am curious if either of my two Pro .46's have a head gasket. I defintely think you got something wrong with your mixture somewhere.  I am curous about the possible leak you mentioned with the head and cylinder liner. If there was a leak there, you would for sure have a lean problem as it would let in air, which would lean out the mixture. I have a VERY seasoned TT Pro .46 that has alot of miles on it and still has descent compression even after 13 years of abuse. Hopefully one of the more experienced Glow gurus will step in with a solution. </p>

Just a side note. I looked through the manual for the Pro .46 engine and it says to ensure the fuels you use at least has a small percentage of castor in it. I had been running pure synthetic up until recently.  </p>