A couple of thoughts: the bi-metal coil is not a common failure, have you removed and tested
it in a bowl of boiling water from cold?
Is the coolant circulating freely through the dome. Those small hoses can easily
block, especially at the water pump end where the spigot at the steel rail is quite
narrow. (easy access past the huge steering gaitor)
The choke mechanism has several parts, all have to move freely on the spindle,
and the small return spring needs to work.
Hope this helps,
Nigel
