Christian McArdle wrote:
When I had the casing off of the actuator, the heat was coming
from the silver coloured drum shaped object - presumably the motor.


I have since left the lever in the central position and the motor has
cooled down.

It sounds like the head is totally knackered. Persist with removing the
thing. Any springs are part of the head and it is of no relevence if they
are damaged or lost.
If I do this, can I safely continue to use the system for water heating
until I can find a replacement?


Once the head is off, make sure the spindle turns relatively easily. If so,
you can probably just put a new head on it. You might even get away with
replacing just the motor bit. It is called a "synchron motor" and is easy to
source if you don't mind a little soldering.
It's 15 years old, so I think I'd probably be happier renewing the whole
actuator.

Am I right in thinking that a plumbers merchant is the place to go for
this sort of thing?


Christian.