Got a 9503 ride on (three bike tow bar mounted type) it is only 7 months old and already two bolts that the fixing arms rotate on have sheared (not overtorqued) Would be great if I could be pointed in the right direction for replacements

I’ve used http://thulespareparts.co.uk/ in the past, found them excellent.

They’ll have every last washer, just pick your bits from the schematic.

Talk to the shop you got it from, Thule’s warranty service is really good IME.