Elan M100 central locking help

[sfl993t4]

Hello All

I have an M100 S2 (borrowed) and the door drivers side central locking has gone wrong. Appears mechanical rather than electrical as the lock goes down, but only shudders when it tries to go up (unlock).
Any idea of the part number of these, whether it is an all in one lock and solenoid etc. and how easy it is to fix? Any other suggestions

[JonRB]

How's your battery charge?

Our SE tends to get a bit cranky when the battery is getting a bit flat and a good charge sorts it out.

[sfl993t4]

Battery is fine, definitely an issue with the solenoid or motor. The passenger side works OK.