Diplomat ACA9102 salt problem?

My dishwasher seems to be dishing out far to much salt, so all my crockery is covered in it. The salt amount ring is on 'minus', and the salt cap seems to be pretty much on (though with this cap it seems to never be able to tighten until you can't, you have to guess which turn is the tightest before it goes back round to being loose again) anybody have this problem and solve it?