I'm running a 2006 Exmark Lazer Z with one of the new 50" triton decks. It's got about 190 hrs on it. Lately it's been cutting really bad and leaving longs strips of grass as I mow. The long strips are not really inline with the front caster tires so I'm kind of ruling them out. I've put brand new blades on it, scraped the underside of the deck really really good, changed cutting heights, nothing is working. The belt has a tensioner and the belt seems pretty tight so I don't think its that. I'm not hearing and noises like it could be a bearing or anything....and my hydrolics are topped off. Any idea what might be causing this????? It's killing my cut times.