Removed the spark plugs and I could see that the #1 and #2 cylinder plugs were fairly carbonized.  So, since I'm getting close to the 100 hr replacement (I use 100LL), I just replaced all the plugs with new ones.

Did the run-up and all was well.  Then did two circuits and the engine purred like a cat. 😎

#1 Top plug.  Pretty carbonized

Especially when compared to the #3 plugs.

I don't tire of this sight.