Hi Dave,
I have just managed to get my BSF S70 trigger fixed, there is a thread on here somewhere with some pictures. You need a good safety pin, of size just under an inch, cut the safety off it and bend the shanks to shape. Mine works perfectly now. There was a guy selling a boxload of parts on here for them, I asked to buy them for us all,(got no response) but someone else did and I am not sure if they actually got the goods.

For info its a bit hard to fathom but when you are ready,lay the rifle on its LHS and the spring mounts on the side facing you.
Good luck.

The armourer