Picking up where we left off yesterday, I went out to have a look at the problem with the Cessna. You will remember that the engine was running rough on the right magneto. It turns out that this was my lucky day since the right magneto runs all the top plugs. That means I can get at them without removing the bottom cowling (big pain in the a$$, right Rich?) I had my thinking hat on and was hoping that it would turn out to be a plug problem. I carefully removed the six plugs and put them on the tester before monkeying around with them. Sure enough, #2 tested bad. That is the plug on the right. I inspected it carefully and found an infinitessimal piece of debris lodged between the center electrode and the ground electrode. I pushed it out with a gap tester and tested it again. Bueno, it was working just fine. I hate it when you can't spot the problem and go through the motions in hopes of getting it fixed. So, I cleaned, gapped and tested them all and reinstalled them. Now it was time for a functional check flight, which I was more than happy to conduct. The run up was perfect, and I checked it again all four times I landed. Everything normal. Returned the aircraft to FMC (fully mission capable) status and recorded the maintenance in the engine log book.