Grohe 1000 shower problem

[BigRedAnt]

I have what appears to be a Grohe 1000 Thermostatic Shower, which has suddenly lost pressure and only gives out cold water. It is linked to a Saunier Duval combi, but the boiler still heats the water to the taps.

My guess is that the problem must be at the shower end due to hot water still coming from the taps, and that it is probably the thermostat; the boiler doesn't fire up when the shower is switched on.

Would a faulty thermostat cause this problem? I presume that the thermostat demands the water from the boiler, and is therefore at fault. Would this also cause the low pressure?

Unfortunately I don't have the documentation for the shower, but it looks like a 1000 model; I will have to take the thermostat out before ordering a new one to get the part number.

Thanks for reading.