I have a Potterton Profile 50e boiler, and lately the (thermal?)
cut-out has started tripping. This results in the pump going
continuously, but no hot water.
It happily resets manually, and starts up again.
It seems to trip 4/5 times a week, at different times/conditions - no
obvious pattern.

Any ideas?

Obviously I am not going to take the boiler apart (unqualified), but
if the cause is elsewhere in the system, I beleive I could fix it.

Neal