I have a MF 50 do not know the year, I bought it in 1999 the engine had a stuck valve after I ran it for a while it loosened up and then it ran ok for the last 15 years. It only had approximately 75 pounds of compression so I decided to rebuild this past winter. It did okay after the rebuild for a while a couple of weeks ago I was mowing some deep grass then it popped three or four times died then it would not start. I checked compression 100 pounds showed on the gauge. looking in the spark plug hole there was what looked like glue, turned out to be antifreeze. pulled the head dropped the pan, sent the head back to the machinist to check it out. looking around the sleeves I noticed that the top of the sleeves moved around and bubbles came out. I talked to the machinist (he is the one who pressed them in) said that the gasket would hold it once the head was clamped down that may be true but I don't believe that the sleeves should move and didn't I do that already when put the head on. Is there someone out there that point me in the right direction. Thanks