This thread got me thinking so yesterday evening I hoisted the mower up in the air and checked the new blades....both have writing on the bottom that say "grass side." So, thankfully I got that right. I spun them around and they nearly touch each other as they should. The bottom of the deck had large accumulations of dirt and debris that has probably collected for a couple years. I thought to myself, this stuff probably isn't the problem, but I decided to scrape the underside clean anyway as that mess couldn't be good for the deck metal....wow what a difference it made in cut quality.