If the compression is starting to go, and you're leaning the engine to compensate, that could be a source, but lowered compression usually affects idle first. The idle and acceleration become irregular or unreliable. Some fuel leaking from behind the drive washer is normal. That's how the front bearing gets its lubrication. If you're getting enough fuel through there that a lot of raw fuel is wetting the aircraft, then the fit between the crankcase and crankshaft is shot. The seal is made by a film of oil between the two. The front bearing doesn't make the seal.

As I mentioned before, if you can mount the engine on a test fixture in the upright position and get everything set up "perfectly", do so. Testing the engine that way will allow you to determine if there's a problem with the engine. If there's a problem, it should show up on the test stand.