Thanks guys,
I'm amazed you managed to press them in. I reckon there is a least 2 or 3 mm difference.
If I was to machine them I would have to get someone to do it for me, not sure where to go for this.
I might take the spring into Pedders and get them to measure it and see if they can source another off the shelf part that will fit.
Cameron at Prospect seems to be pretty helpful so far.