Can Anyone Help !!

[Dazzallix]

My 00 ML has started having trouble with the central locking,Occasionally as seems the case with this car... the drivers door will rapidly pulsating 3-5 times when the door is trying to lock,this is quiet noisy and is over in a matter of a few seconds,However sometimes it locks sometimes it doesn't,other times no such problems.
Only started doing this now for a about 3 weeks on-off,i had the door trim off with no visible signs of any problem ?

Dazza

 

[Bob.R]

Pulsating central locking is usually caused by the mechanism sticking on the affected door. The lock cannot travel to its full extent and returns to unlocked/locked several times. lubricating the mechanism and rod pivots normally cures the problem but slight adjustment may be required.