I don't know how similar it is but I had a problem with the rear door handle on my Disco. The door would lock and unlock but not open always open. :(bigangry):
Sent for a new spring of Ebay(can't remember the price but it didn't cost a lot).
Fitted it in an evening, a bit fiddly though. If you still have doubts about fitting this spring, I did it with one arm(I only have one arm due to an accident many years ago)
Haven't had any problems opening door since fitting this new spring. :(biggrin):