Hello again,

Just to say that I have received two thermostats from BES. I believe
they are made by Banico. If I have a slight grumble it is that only
60C is marked on and the other temperatures are "max" and "min",
whatever they are. Also these are marked white on white, so they are
difficult to see. OTOH I suppose you only have to set it once.

When I changed the bottom thermostat there was some fine white powder
inside the immersion heater. Whatever could that have been? There was
no powder in the otherwise identical top heater.

The head of the slotted nut that retains the cover on the one heater
is a bit chewed up, making it difficult to grip with a screwdriver.
Any suggestions on how to grind a new slot into it?

The new thermostats have a small metal disc on the rear, which I
presume is the safety thermal cut out. Should this be touching the
cylinder, because I'm afraid they don't in my heaters?

Thanks again,
Stephen.