Toyota Repair: Toyota Corolla Door Lock Solenoid, toyota corolla seca, toyota corolla

Question
Hi - a friend has a Toyota Corolla Seca Conquest (199?).  When the doors are locked/unlocked with remote or centre console switch - the drivers door does not always lock or unlock.
The solenoid is definitely operating, but not moving the mechanism.
I have removed the door casing and applied lubricant to ensure no friction in the mechanism - but no improvement.
The mechanical operation of the door lock soldier button is no harder than all other doors.
Is there a known problem with the solenoids wearing out on these models ?  Or is it worth removing the whole mechanism from the door and overhauling it ?
Thanks for any help you can offer.

Answer
Other than those little plastic clips that secure the metal rods to the components there are no replaceable parts available.Sice the problem is intermittent I would rule out a mechanical problem, electronic components are much more likely to have this kind of problem so I would replace the lock actuator.