greetings, i've got a john deere lawn tractor (x300) with a 42" deck that i use on my own residential property (1/3 acre). it is not "the true mulching deck", rather its just the standard deck with side discharge with standard mower blades. after mowing with it for one season, i switched to "gator mulching blades" at the recommendation of a friend. they seemed to work fine and did not have any effect nor did they cause the mower deck to vibrate. smooth as the day i bought it. but, after speading new mulch in my mulch beds, i decided that i was getting tired of side-discharging clippings over mu new mulch...and i didn't like always having to mow in one direction to minimize to direct the discharge away from the mulch beds (foundation plantings). so, i decided to buy a "mulch kit" specifically made for my mower by john deere. i thought i was just buying some sort of plate that would plug the side discharge...as well as the new mulch blades that come with the kit. WHAT A JOKE!!! when the jd parts guy came out with the "kit", it was in a huge box. i opened the box and found this huge plastic contraption that slides in the side discharge opening and fits across the entire front edge of the deck and wraps around the side of the deck to plug the side discharge opening. its supported on the discharge side by the lip on the deck itself...and is secured on the left front with a bolt/wing nut. this plastic thing seems to occupy 8" of the underside of the front portion of the deck...leaving just enough room for blade clearance. well, i installed the thing...and the new mulch blades...and started mowing. admittedly, the grass was a little taller than i normally keep it due to lots of rain. when mowing with this new "kit", i seem to notice the deck/mower felt as though it was vibrating while mowing grass. noticably more than without the mulch kit. also, it didn't seem as though the quality of the cut was as good as the gator blades or the standard blades that came with the mower. i was seeing several blades of grass that weren't being cut and it was if i had to go over the mowed areas twice. also, i slowed down the speed at which i mow...but not the engine. yeah, it's mulching the clippings better than without the "plug" and i didn't have to be as concerned with getting grass clippings in the mulch beds...but i don't think i'm happy. any ideas why the cut isn't as good OR why i'm getting vibrations??? i realize with mulching, you have to mow FREQUENTLY and not let the grass get real long. but, this vibration thing is troubling and i'm afraid i may wind up destroying spindle bearings or worse. also, slower mowing speeds make this job too time consuming...especially when i'm not getting a good cut and having to double back to get the un-cut blades of grass i'm finding. any ideas???????? thanks for the help!!!!!