I've got the 3 Hircine Totems (and prayed at all of them).
I've done interminable Animal Extermination quest for Aela.
I've done all available other Companion Leaders quests (now when I click on them I only have the options train or Follow).

What have I missed to trigger the Werewolf Cure quest 'Purity'? If I have to trek across any more mountain paths to kill yet another Snow Bear/Sabre cat etc., I'll screeeeeeeeeeeeeam ...........

You cure youself on the last quest of the companions quest chain, where you free Kodlacks spirit.

How do you actually cure yourself? Once I was able to put one of the witch heads into the flame and I killed my ghost wolf. But I reloded the save and I can't do it anymore. How do I cure myself? Do I have to do their quests?

Once you've done a quest for Aela, wait a couple of days before you speak to the others. Their dialogues should pop up. It did for me.

Oh no, that was about 10 hours of play ago - if I just go back with a Witches Head now, will it still work?

Ahhhhhh, ok, I'll do some other quest and then go back to the Companions.

Two days (RL) later - doing Companion quests (rinse repeat). Just done one I've done before - same house, same beast ....................... same frustration.

Any advice?

Some things I believe I seen people mention that can screw Purity up:
1) If you don't get all 4 heads the first time it can mess it up.
2) If you store the heads before getting Purity it can mess it up.

I may be remembering those incorrectly, but I know that I got all 4 the first and only time I went to Glenmoril Coven and did not store the heads until after I got Purity (the quest didn't actually remove the heads from my inventory when I cured Farkas and Vilkas or Kodlak for that matter) and I got the quest.

It should work yes.

And about the purity quest: I think it can get bugged in several ways for me it got screwed up when I got the purity quest and was about to go to glenmoril cave (I only took 1 head when I was there the first time) with Vilkas. The questmark pointed on the door out from Jorvaskr but when I steped outside the questmark still pointed on the door to Jorvaskr (wanted me to go back in) and Vilkas stoped following me. So I loaded a save just before I got the quest and went to collect the heads of the witches and then traveled back to start the quest. Didnt get the quest.... so I just left it like that, couldnt be bothered with more of thoose simple tasks.

Ahhhh, I got all the heads when I went there for Koliak or whatever he's called. but I've been storing them - I'll have them on me and see if that triggers Purity.

Thanks everyone - it's such a pain doing these silly little Kill Criminal, Kill Snow bear quests I was kinda giving up on the whole cure thing - but now I've some options to try tonight. Much appreciated.

Hopefully that'll work.

SUCCESS !!!!

Having the Witches Heads in my inventory didn't work ..... until I also put the sword (Wulfrun) in my inventory as well.

(I had sold it but got it again from the tomb), zapped back to Vilkis and got the Purity quest ......... at last!!

Thanks for the help - much appreciated - would still be trying to trigger it in a month's time otherwise lol