how to replace backflow valve in B&G Chek-trol?

Nom_Deplume

The flow check valve (I hope this is the right term...the valve that only allows water to flow one way) built into this pump isolation valve has become increasingly noisy. I couldn't find any way to remove it in a non-damaging fashion.



I am able to turn it but it doesn't unscrew, it just turns in place. I was finally able to irreversibly pull out the ball and spring, so now there's no noise, but the rest of the plastic body is still in there. I'd like to remove and replace it so I have a backflow preventer again. Is there a trick to it?



Many thanks!