Have just noticed the Gold Bezel on this 501 has cracked - would it be something I would have to send to Omega for repair
OP, where in the world are you? Omega themselves wont be able to help, but there are specialists who can fabricate replacements. I know of 1 in the UK but there are likely also people in the USA etc who can do so also.
This is the person you want in the US: https://www.watchcaserepair.com/ Not a cheap fix, but his family has been in the watch case business for generations. A good custom jeweler might be able to repair the bezel if you are already working with a watchmaker who has the tools to remove and replace the bezel properly. gatorcpa
Whilst I was at my watchmakers a jewler came in to the shop and hearing that Sesphas could not the bezel offered to make it good - so look forward to the watch becoming whole again.