I was mowing a really overgrown field today, deck all the way up then going back over it at 3.5" and my deck started to vibrate. Stopped the engine looked under the mower, and my mule drive pulley from the engine had come unbolted!!! The mule drive pulley was just hanging there, how in the heck did a three inch bolt come undone?!?!?!? Lucky for me I found the bolt and washers and had to pick it up with a t shirt. Will put it back on tomorrow, I just wanted to know how this could have happened. I dont wont to pay $35 for a bolt and washer set when it does it again. I already have lost a scalp roller this way. I had the rollers set at 2.75 and was mowing at 2.75 and somehow it came off and of course I rolled over it. That is not something you want to run over trust me, which was a nice $25 to replace. Any suggestions?