Cheers your instructions helped. I've done the first bit only and removed the spring. The Standard
Bsa rear guide looks well made just its a very loose fit. Luckily I had a spring from an old Diana in my box of spares that was same length but a lot tighter fit on the guide. Just rebuilt using a Diana spring and it feels a lot smoother to fire now and the twang noise has completely gone. Will chrono tomorrow and see what the powers like