Remove cartridge holding nut inside Sigma shower assembly

[Adam Baldwin]

I am trying to replace cartridge of a Sigma thermostatic shower set with two volume controls. I have taken apart most of it but I am stuck at cartridge holding nut. I have tried to use a wrench but it slips off. If someone has dealt with Sigma cartridge assembly in the past, any suggestion on how to take it out? Thank you.

 

[Tania Lis]

I am trying to replace cartridge of a Sigma thermostatic shower set with two volume controls. I have taken apart most of it but I am stuck at cartridge holding nut. I have tried to use a wrench but it slips off. If someone has dealt with Sigma cartridge assembly in the past, any suggestion on how to take it out? Thank you.

Adam, did you figure it out how to get the holding nut off? I'm having the same problem. Thanks in advance for your reply.