It depends on the type washer thats with your SP10, I have had a few through here - the current one have a flat on top washer with a bushing part through the platter - it use a M3 x 12MM screw. I have had others that have a countersink on top the washer too - they probably don't need to be 12MM long is my guess. If you want drop me a PM and Ill put 3 of them in the mail to you.
Good Listening
Peter
Good Listening
Peter