Last year I had this problem. This year I'm having a problem with the mulching mower not mulching. The grass is clumping up and clogging whatever you call the 'chamber' where the blade spins and is supposed to chop up the grass.
It sounds like it's running high or faster, based on what I did last year with the throttle/governor spring. Could this have anything to do with it?
I've had the blade sharpened and balanced recently by a friend and it is plenty sharp. But I think he only sharpened the front main edge. Are there edges on the back edge where it's turned up that also need to be sharpened? Does this actually cut, or just force the cuttings up so they can be chopped up more?
I generally mow when it's dry.
I usually cut it pretty long, on the 2nd or 3rd highest setting, going by those notches and ridges where you manually change the height of the mower near the wheels. I've read you're only supposed to cut 1/3 of the height. I'm not out there measuring it, but sometimes it's been longer with all the rain we've had.