I currently have an SMK B-2 (rubbish I know but its a start, will take ages to save for my HW77 ) Its had a twangy sound since I got it and after a proper lube and clean today with proper grease it hasnt gone, I was hoping it would but it hasnt. It sounds like maybe the stock is vibration on the actin but im not too sure. Tried tightening the screws right up but they dig into the wood even with washers fitted. Any help on this one please guys?

Looks like you have done everything you should have- my friend had a B2 and he had the same problem. I really don't think you can do anything apart from buying a new spring. I would sell it and make that HW77 come sooner!