Closing mechanism on rear door

[Jonathan Hearn]

Hullo dear Nissan owners. We love keeping our old Nissan's in top shape. Our 1992 safari long wheel base still purrs at 320000 KMs 

However our 1991 camper van while still purring, has developed a door mechanism problem no one local and lots of time dismantling things can solve.

The rear lift door has a motor which pulls the door nicely tight then should stop. It does close it properly for a few seconds during a clackity episode, then opens again. We found after several hours that if I pull out the fuse while it is making the clackity sound, it stays closed. To open it, it is necessary to replace the fuse and wait for the noise to stop..at no stage does the outer or inner handle do anything any more. Any clues to a fix would be most welcome.

I've fiddled with the button which I guess is meant to switch off the motor when closed tight, thinking it may not be earthing..no luck.