Thanks guys. I think the level of damage has occurred to the spring when I let someone use it and they told me the pellets were dropping through the barrel. They were using .177 in a. 22 and it was probably dry fired it before they realised.

I'm not sure if anyone has a spare or knows the dimensions of part W109? It allows the maxi grip securing screw to sit proud and act as a scope stop. Mine has been put somewhere safe.