This is my third lot of belts, the strimmer just chews them up, not the belts problem bad design(?).
Next to go will be the motor pulley, cvan only be bought as a complete assembly, rip off.
I noted on you tube that to overcome the problem of the belt coming off and being shredded he had screwed a bokt and washer into the end of the cog. I followed his example. The belts are robust