Pretty common for the nuts to loosen and an arm to come off. My issue is with some semi sandy soil. If the tractor hits a soft spot the wheel digs in and starts spinning causing it to lose traction. The arms keep spinning while its digging in creating a hole in the yard that is washed out by the power of the water as the arms keep swinging. Doesn't take long in sandy soil to create a crescent shaped hole in the yard about a foot deep.First mishap today...one of the arms came out and that stops it in its tracks while just open pouring water out. When I got this from a coworker, I never checked the tightness of those, just adjusted them and let it fly...so hopefully this was a fluke due to me not checking the compression nut to ensure it was snug. That spot in the yard is extra soft right now but should be nice and green in a few days!