Yes I worry about the plastic heads. I have changed how they are mounted since but it's a matter of time...not sure about what pumps I'll end up with yet, cheers
I bought the SS head for my KK pump, leaked like a sieve around the contact with the pump body. Had it replaced and the second one is spot on. Mine might have been a one off dodgy one but would just recommend to get it locally if you can so that it can be returned easily if no good.