Get the #4 cylinder to the top of its compression stroke and put some compressed air into the spark plug hole. Listen at the intake, exhaust, and crankcase for air escaping. That should pinpoint the source of the compression loss. Then you can decide how to deal with it. I'm going to predict you've got a stuck or burned valve. Be sure all the rocker arms have at least some clearance at TDC compression.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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