I have a still functioning Varia HL500 which can not longer attach to the bike mount. The plastic bracket that is bolted to the light with six bolts has lost the rim that holds it to the bike mount when you rotate it. This cracked and came off when the light fell off going over bumps. It is simple to remove and could easily be replaced but I can't seem to find a part - checked aliexpress and tried google but no luck. Does anyone know if this is replaceable, seems a shame to chuck a perfectly good light due to a 25c bit of plastic.