What percentage of mower manufacture problems come from their in house work or from components bought from outside sources. I notice they change vendors more than we would think, is this for a cheaper price or better component. I bought a new anti scalp wheel for my Super Z this week because I eased up over the edge of a stump and cracked the center. I brought the wheel home and started to put it on and I noticed a difference, I actually like the one I had just bought better than the original ones that came on the mower. I went back to the dealer and bought 5 more so I could change all of them. I told him to walk outside and see if he could tell the difference by comparing it to one on a new mower. He said yes, that wheel must have come from a different vendor or the same company changed the design. The old style was more rounded with a pronounced higher area in the center and the new one was not peaked as much in the center with more of the wheel able to take the load across the surface instead of wearing the center totally. I would say it probably does not make a hill of beans but I just like the way the new style looked.