Thanks for the replies.
I know it sounds the obvious thing stop pressing the button but it's literally going a couple of cm too far and has cracked the current hood as it fairly shoots up when it comes off the rams. No way to move the pole sadly.
It's only become an issue as I'm having a replacement hood painted and tarted to smarten everything up & you can guarantee I'll do it first time out !!
Sods law in action.