I have a concealed shower control which has a flow control and a separate thermostatic temperature control (Trevi Outline). The flow handle controls two 1/2 inch ceramic valves via a gear-wheel assembly. The cold flow ceramic valve had seized in the closed position.
Having take the various assemblies apart without problems, I started to remove the ceramic valve using a box spanner as per normal procedure. It unscrewed without any obvious difficulty but when I removed it, only the brass part of the valve body came away leaving the ceramic and plastic parts inside the brass manifold. I have now managed to remove the ceramic and plastic valve innards without breaking them, but the plastic/nylon valve body remains stuck fast inside the manifold and nothing I have tried can shift it.
I've used a pair of pointed-nose pliers to try to shift it but only succeeded in breaking off parts of the body moulding and the thin web between the ports at the bottom. The valve body remains stuck stubbornly inside the manifold. As an aside, I'm confident that none of the small bits I broke off have fallen inside the manifold.
I'm thinking that the only option now is to attack it with a *very* narrow hacksaw blade, should such a thing exist, or a needle file. :( I'm hoping that someone else can come up with a brilliant idea that has eluded me?