I just got under my brush hog and I see that my blades need some attention. They are mounted with a single bolt and I can access the 1½” nut through a hole in the deck. When I tried to loosen the nut I found that the bolt just spins and that I need to hold it in place. The head of the bolt is round, not hexagonal and without any obvious way to hold it except maybe 1. A pipe wrench 2. Tack weld it to the blade temporarily? What do you do? Why are the heads round? Some I saw at Tractor Supply are like that too. Seems nuts. Another issue is I believe the bolts may be worn so that the blade or blades are moving up and down striking the underside of the mower deck and making an awful racket. Does that sound feasible? They don’t always bang but they bang enough to be concerning.