I seem to be breaking a lot of shear bolts on the second stage of a 47" snowblower attached to my JD2210. The original seemed to last quite a while. I have a lot of gravel around so I expect to break some but I don't expect to be breaking so many bolts compared to how long the original lasted. The bolts are supplied by my local JD dealer. What grade bolt should this blower be using? Is there something else I should check? Everything seems to be turning just fine.