Oddest failure i've ever seen - Simmons Blazer 3-9x32mm Rifle Scope

This scope worked just fine for a few hundred rounds out of a heavy barreled 10/22. After almost 3 years, I noticed grabbed it to shoot a varmint and the crosshair was off. Huh, the scope is still tight, the heck? I cranked the power ...and the crosshair moved some more. So, somehow the crosshair is now on again, off again spinning with the power adjuster. I even super glued it to 6X and shot a group, nope, it's throwing big groups all of a sudden. So, I'm not sure how that happened, but it's done.