So I assume there is something similar to stop the rear pane sliding forward.
Thanks
Garry
This actually stops both by pushing up on the bottom of both in the middle where they overlap, this one is worn and you can see how its gone thin and sort of wedges between the two, the "spring"is also cracked and lost it's tension, that's why I took it out as it didn't work anymore
sorry this is the only photo I have
regards
Scott