Inside my thermostat housing is a thermostat "held" in place by a spring-like piece of wire that locates inside a groove in the housing, but the thermostat is rattling about.

Now, is that normal, does it locate in place with water flow, or, should there be a rubber seal in there to positively hold the thermostat in place ?

If so, what is the sequence for re-fitting, seal, thermostat, spring, or, thermostat, seal then spring ?

Thanks in advance