Can't say that it was done well. First I hacked a chunk out with a utility knife, but should have used a serrated blade. Then I have a filing tool that is a half-moon on one side and flat on the other with course and fine on each side. Spent an hour or so filing the seat down to where it is nearly flat. The seat cover hides all my imperfections but I knew that going in. Now I can easily slide back and forth on the seat.
What did you use to shave the seat foam down? Thanks
Note, this is extremely messy. Do it outside.