I am also having an issue with grass build up under the mowing deck. I also do not mow when the grass is wet but wait until a little later in the day when dew has evaporated and the ground feels dry. I have a Troy Bilt Pony with high lift blades and never cut lower than position 3 (mid point on the lowering mechanism). It gets a bit frustrating to have to scrape out underneath the mower every time it is used so I am looking for a solution to the problem too. The blades are new high lift, having been fitted in the last four weeks. I read with interest about speed, slowing down your mowing. Presumably that means your forward speed?
I bought my mower in April 2014 and never once had an issue with grass build up until now, so I wonder.... what is different?
I was also considered using mulching blades bought for my old mower, part 742-01-610A and asked a question about using those in the Lowes question area. Interestingly, the answer from Troy Bilt was, "Those blades are too short for your mower". In fact, they are the same length exactly. Could these blades work and help prevent grass build up?