Sell the van would be the best fix for this. You can pop off the plungers portion from the sliding door. Take the assembly apart and you see where the plunger rods pass through metal relay looking things. That may be where you are loosing continuity to the plungers. Take it all apart clean it and try to bend those relay looking things to where they will be tighter on the ringer rods. Put it all back together and turn the slider off manual. It is easy to fix but the assembly will fall apart on you but don't worry you will figure it out