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I am pretty sure someone here posted a cool fix. Very early on, I took a piece of heater hose and jammed it between the lamp holder and the bottom of the bracket. No vibration, no failure. Sorry if its too late for that.
A replacement isn't cheap. I would check if it was the improved part prior to purchase...https://www.harpermoto.com/product-30401.html
Is your bracket the old shape? The newer shaped bracket has a wider base. Newer shape, on the left, has been fine for about 35k.-the old one broke even after repairs.Circa 2011:Edit: circa 2007