Jaguar, S-Type, 2001, v6, Automatic

When I open the doors with key fob, they automatically lock again.

I notice that the small black locking handle on the front passenger door does not flip out the way all the other door locking handles do. If I manually position the front passenger black locking handle in the OPEN position then the doors autamatically open when I try to lock the doors with the central key fob. So it appears that whatever position the front passemger locking handle is in controls the central locking system.

I assume the fault lies with the locking motor/solenoid which controls the front passenger door which may need replacing or may need lubricating.

Can anyone shed any light on this problem please?
Does anyone know the part number for this motor/solenoid to fit my car?
As an engineer, I am mechanically adept - is this something I could replace my self or does it require specialist skills that only a garage can provide?

All help appreciated.