i think Labour does have a much wider problem with the return of a great many cranks, oddballs, wierdos, CT's and downright unpleasant people that the party had previously managed to get rid of.
it is connected to the Corbyn thing - its not Corbynites are all nutters and loons, but in practice it is very clear that the rules, procedures and attitudes that the Corbyn lead and favouring internal party structures have encouraged and allowed - along with large numbers of very normal, very decent people into the Labour party - a cohort of people we'd previously got rid of, or who had been refused membership, into the party.
my branch chair, and all of the other CLP officials i've spoken to, have said that the Party structures no longer allow the CLP's to warn off the central party about 'undesirable elements' because the central structures don't want what they see as non-Corbynite individials (whether they are or not..) acting as a bar to Corbyn supporting members. those central structures are simply not interested, and infact they see any attempt to warn the central structures about particular individuals as an attempt to subvert the leadership.
it is that paranoid, and that poisonous.
its up to you as to whether you think the party machinery is cynical enough to think that it doesn't matter how obnoxious an individual is as long as they vote Corbyn in the next leadership vote, or whether you think that the party leadership is happy to flood the CLP's with loons and wierdos if that provokes a proportion of the CLP officials who keep non-Corbynite MP's in their seats to leave in disgust and frustration.
you're right, it is the Tories making mischief - but who gave them so much ammunition?