Cleaning Tunze powerheads

[Dash]

Arghh a bit frustrated trying to do my cleaning. I can never open these guys up - is there a secret? I do have very weak grip (had carpal tunnel) and my hands are small so that is a problem. I wish it was a twist off but you have to sonehow press and pull?

I hate having to ask for help every time I clean these. Hope there’s a little trick I’m missingl