912S low compression 1 cylinder

Resurrecting this post as it has now happened to me.  Performed a compression check on all cylinders during my annual earlier this week.  Cyl #1 was showing 60.  All other cylinders were normal.  We ran the engine and re-checked it.  Same result.  You could hear the air coming out of the exhaust pipe.  It's a 912iS with 1,266 hours on it. It has always been run on 93 e-free MOGAS.   Lockwood has asked us to send the cylinder to them which we plan to do on Monday.  Any ideas on what's going on?

Have come across the recommendation to fly the plane for 20-30 minutes and re-test right away after landing. Ground runs may deliver a better result than testing a cold engine but a proper flight is said to be the better test preparation. I‘d invest that time before pulling the cylinder. Tried a borescope yet to check the condition of cylinder and head/valves?