hey guys

just realized my rear passenger side door lock seems to be getting little to no power when attempting lock all doors at the same time using the switch from the front driver and passenger side door lock switch. i was just walking by my car just now and just said what the heck let me see if all my doors are locked and that one was open. luckily nothing was stolen. i turned on the car and tried to switch it from open to close and sometimes it'll close and sometimes it wont. it would never fully stay open or closed but just stop half way or flinch. what can this be?

 

lubrication