I have a home edition Lawnboy ZTR that started to make a really bad grinding noise like the spindle bearings went out. one of the spindles was missing a bearing shield so I though it was that one. I fixed it, but that wasnt the problem. The noise is still there and the cut quality keeps getting worse. It leaves two strips of grass which looks to the width of the middle blade, and it cuts to the dirt in the middle of each pass. Ive narrowed it down to the middle blade. I thought a blade was bent(time to change blades anyway) so I bought new blades. That didnt fix the problem either. What would you recommend to fix it? im getting a new mower but need to have this one fixed before selling it.