Being damp inside the ignition cover is one of the signs of a bad left seal. Typically, it sucks air in causing the lean condition. Quit looking in the cover and look at the plug! I seen a guy rinse out a trans once. Gasoline has an inherited trait of making the metal shavings stick to the inside. It is also not good for the clutch plates. If your plug is silver, metallic looking, then part of your piston is already gone, you can look in the exhaust port, that is where the piston will blow off. And, flushing the trans would have an effect on the right seal, impossible on the left.