Hello hello what's going on here then.

[MikeSharp01]

Spotted a leak coming out from under our ensuit bath last evening. Traced it to one of the taps being cracked open and a leak from the diverter valve that had found a hole in the silicone seal. Have got the bath out but before I take the diverter to bits I wonder if any body knows what I will find in there. The diverter button assembly looks to have a couple of flats on it so I assume it unscrews but I thought I would gather the collective wisdom before I tried.

[Jeremy Harris]

Looks like a @Nickfromwales job to me!

 

The diverter valve in the shower/bath tap at our last house constantly gave problems.  That was a lever operated valve on the shower valve assembly that just selected shower or bath fill, and the failure point was an O seal.  Taking that apart was easy, as the handle came off by just removing a screw under the cap on top, then the cover sleeve pulled away, revealing a brass nut that secured the valve shaft in place.  The O seal that kept failing was the one that sealed around the shaft, with the failure always being due to scale build up.

 

It's not clear from that photo as to how you get the thing apart, though.  Your guess of just trying to unscrew it seems as good as any, and one that I'd (gently) try if it was mine.