redring 7x shower

hello

got a good but old redring instant 7x shower
was working great
suddenly the water stopped flowing through
I cant even get cold water to flow
took off cover and checked inlet flow and water flows when tap turned on.
However the water does not go through to hot cylinder.
The hot / cold switch is where the water inlet flows, and for some reason
does not flow when I reinsert switch.
I expect the hot/cold switch to control temp but not have any effect on flow, or am I wrong, there is no blockage in pipes to cylinder.
it appears to just stop flowing.
I noticed the switch mechanism has a small ( wheel type
small unit) within its mechanism.
Does this mechanism rotate to allow flow
through to cylinder.
I cant find a manual for the shower anywhere online to help with problem.
Anybody got any ides on the flow

thanks a million

I never heard of red ring. What is your location?

Itawelsh, this forum is primarily based in the United States and Canada. According to your IP address, I see you are posting from Limerick, Ireland. Maybe some our members who are familiar with plumbing in Ireland could possibly chime in?