Have a 4 year old eXmark radius, 60” deck. First deck belt lasted about 400 hours. Got a replacement at Rural King (dealer wasn’t open), it ran about 8 hours then disintegrated. Got a replacement from the local dealer, have run it about 8 hours, just came loose. I checked the deck pulleys, they turn freely, however the spring loaded tensioner / idler pully is floppy, is that normal (Might be that way to compensate for differing deck heights). Anything else I should check? I mow a lot of fairly high grass, so things get a workout.