I originally purchased a JD Z-trak 717 that had major hydraulic problems (would not back up when it got hot). After 3 repair attempts in 3 weeks JD purchased it back from me and I bought a JD Z-trak 757. Now each time I mow I break the deck belt. I've mowed twice (3 acres) and both times I have broken the deck drive belt. Other than this anoying (and expensive - $53.00 each time to replace it) problem it cuts and runs great. Any idea what would cause this? 5 repairs in 5 weeks - nothing breaks like a deere!! (100% failure rate).