My chlorinator lid is stuck and it won't budge

[aces79]

I have a Hydrotools chlorinator. It's 2 years old and it's always been hard to open. We've lubed it, greased it and replaced the o ring.
We usually open it with a big pair of pliers but that's not working today.

The lid won't move at all. Ideas for getting it open without breaking the PVC pipes running in and out of it?

 

[Pv2]

sometimes if you try to tighten a bit, it will actually loosen things. have you tried that. good old percussive maintenance is your next choice. if it is a total fail, cutting it out and inserting a slip joint and new pipe will work. we mostly use salt water chlorine generators or liquid chlorine around here, so for the few times folks might use tabs a floater in the pool is fine.