Walk Behind Lawn Mowers

I purchased a HU700F walk behind lawnmower in April and the side discharge chute (discharge deflector, part #: 5324394-30) broke in August. I only use the side discharge chute and it is poorly made, falls off all the time, and now has broken. Part of the problem is that it is only held in place by the open mulcher door instead of being permanently affixed to the mower. Is this covered under warranty? How do I obtain a replacement? Is there a way to permanently affix the side discharge deflector or is there a reinforced model? I purchased the mower at Lowes and if I have to go to a dealer, will I be treated the same as if I purchased the product there??? I would rather just get a replacement part and do it myself; is this possible?