Alterna Amala concentric thermostatic mixer valve Shower cartridge replacement

[Jredmond]

I am replacing a new shower cartridge on a Alterna Amala concentric thermostatic mixer valve
I was sent the wrong part , so i am awaiting the replacement .However when i reassembled the old one i was unable to move the shower lever ..So my question is when i fit the new one is the cartridge when screwed in just hand tight or should it be nipped up .and the cover over the housing should that just be hand tight .I did take it apart and just put the cartridge hand tight it seems ok , so still unsure
Thanks in advance

 

[Aquarius]

Usually hand tight and nipped up.