I had the same problem, mainly duie to the dealer not taking the time to adjust correctly. I adjusted the deck up to almost 3 inches but then it was slamming into bottom of mower, this eventually broke the piece that connects the rockshaft to the adjustment arm. This piece was under warranty and evidently a problem because they changed the design, after installing and adjusting the rockshaft as well I can cut at 4", and it does not bang into bottom of mower.