Carb for ETZ 251

[treehouse]

Hi, I've got to replace the carb on my 251 and wondered if anyone here has any advice. I'm thinking there's a bit too much to go wrong getting a used one, but I'm open to suggestions. I could get a new Bing for about £100+ or there are unspecified make ones on eBay (new) for about £50. It's a Saxon Tour and AFAIK doesn't have anything else major wrong with it. I want to get it running, but very probably to sell. I paid £660, and obviously don't want to lose much in the sale (or make a bit). Any thoughts, advice or offers gratefully received. Also, if I went for the Bing, it says there are male and female fitting ones, but the photos are the same - how do I tell which I would need? Cheers.