You are on the right track - I tried the washers on a bolt and bent some blades on my 1430. After some trials, found that a piece of truck tread makes a nearly indestructable bumper. Find a chunk along your favorite highway (wear gloves - lots of steel strands) or just borrow an old tire. To make washers use a 2.5 inch holesaw and a strong 1/2" drill, lots of lube (armorall or detergent/water) (it helps to drill from each side) - mine have a lot of steel in them and are about 1.5" thick. Drill a 1/2" hole through the rubber piece after you get it out of the holesaw - put a thick washer on the bolt and drive it through the rubber "washer" and install two of these into the spare holes on the brush cutter. Compress the rubber washers a quarter inch or so to make them really firm. You will, now have crash-free starts and stops, and the impacts from hitting solid objects are much reduced. If you find you are breaking or bending the bolts holding the rubber "washers" when you hit objects with the center of the mounting drum, try compressing the washers more. I have not broken any bolts or bent any blades since installing these.
