I'm not sure momentum are really a problem - they seem to actually have a reasonable grasp of the situation. It's the aging time-served cranks who're shitting it right up.Some expulsions, political education, and getting a grip of local branches and Momentum might have helped a while ago, now I'm not so sure it can be done. It's a problem in the left outside the Labour party as well, and that's not being dealt with either.
Clive Lewis wrote an ok article for the Independent the other day, but it's difficult to imagine such a programme being rolled out under current conditions.
Opinion: I know that Labour can rid itself of antisemitism – here's how