Grohe shower with body sprays - broken tub diverter valve?

[Keyhound]

Hello,
I stumbled across this site for assistance as I am not handy with plumbing and need some direction. I have an older Grohe shower with multiple body sprays. I just noticed that, although the shower valves work fine, the tub valve does not work and no water runs out of the tub valve. Knowing that the shower is over 20-years old, are the parts still available to repair this tub valve problem? Seeing the photo provided (I do not have any model numbers), can someone tell me the part number that I need to order? Much appreciated from this terrific resource!

 

[Breplum]

First turn water off to the dwelling and disassemble the valve.
It is I think Ghromix wall mount volume control. They came with either 1/2" or 3/4" connections and had different renewable seat and ceramic cartridges.
I only have 'old' product numbers
The 1/2" seat 45023...cartridge 45822
for 3/4" seat 45345 " 45888

 

[Sponsor]

 

[TJRAD]

question: I see three volume controls....I assume one for the hand spray , one for both body sprays , and one for the tub spout...what is the reason for the diverter on the tub spout? just throwing it out there...why does your tub spout have a diverter ? maybe someone couldn't find a spout with out the diverter so they installed this one instead and now the diverter is locked up in the diverted position and water wont come out. just a wild thought.
on the flip side maybe the volume control is just simply broken and Breplum is right ...it needs to be dis-assembled and identified and replaced. most grohe cartridges have the model number stamped on the side.
Good luck.