I have just done a longer test getting up to temp and seems like I have a few leaks around the steam boiler that could well have led to thermostat failing. It seems like pretty much all of the quick connection fittings are leaking slightly from where the pipes insert.
Do the washers or whatever in them have lifespan?
Can I do anything to stop the leaks or do they need replacing?
Guess the lesson may be to do an occasional test of getting up to temperature with the lid off to check everything is ok as didnt notice a change in noise or any water around the machine. Unless the leaks were just caused by moving the machine around to sort the thermostat problem.. who knows!