Bought five of them from DMGRS, and helped a few local owners in need. Always found Mat to be quick to answer & polite:
https://www.dmgrs.co.uk/search?type=...=gold+resistor - but my new fan with a silver resistor is now about 4 years old and still going stong. Have helped others locally with new fans that come with silver resistors too and although I advise on checking them regularly, haven't heard of any failing.
Perhaps these new non-bayonet fitting fans have differently rated silver resistors and it's generally the older, original ones that fail?
Keep well