UKC

so my latest rab feather jacket has come to the end of its useful life because the zip is totally buggered. I'm reluctant to part company with this trusty servant so has anyone any advice as to how to replace the zip with one less broken?

https://www.scottishmountaingear.com/repair-service/clothing-repairs did a good job replacing a zip for me.  There is a fair amount of work involved and so it's not exactly cheap, but a lot less than a new jacket

Rab did a full replacement zip on my down jacket 2-weeks ago and did a fantastic job.  Cost £30 inc postage both ways.

https://rab.equipment/uk/service-centre

If you can sow machine cut the teeth off each side and your left with enough to sow onto saves all the unpicking ( and the ducks trying to fly again) will not be neat  and posh but keeps the wind out 

I work in an outdoor shop and I see a lot of jackets with broken zips that aren't actually broken. 9/10 times it's just a matter of replacing the runners. Closely inspect all the teeth, as long as none of those are ripped off then it's a matter of a couple of minutes to replace the runners.

Replacing the entire zip of a down jacket tends to be a hassle and it really depends on the construction if it is possible at all. 

Thanks for the advice. Where would I get runners from? I guess they are specific to the zip. Very happy to give your suggestion a go. 

Your zip will be made by YKK and you'll probably need a size #10 or size #5 runner. If it has plastic teeth then search for YKK Vislon

A new runner (maybe search for zipper slider) will cost under a fiver.

Also try lube, and using some pliers to nip the runner tighter (vids on YouTube) before going for replacements. 

all of the teeth are present but some appear to be damaged. I'll give your suggestions a go before committing to a new zip. thankyou.

that seems to have done the trick - thanks.

have you any advice on pocket zips that don't have the starter, the broken zip there leaves the pocket open and makes a cold bridge.