I think this is probably been covered before but just double checking a thing or two.

I've noticed my chain has been marking the left hand side of the tyre. With the SD needing an insanely slack chain is this just part of SD life or is it a sign that the chain is cooked?

The sprockets look like they have heaps of life in them and the chain sits pretty snug against the rear sprocket when testing the chain's condition in that way. Chain tension is bang on the 7mm distance from the swing arm at the point where the chain guard bolts to it.

I can only assume that a bit of wear in the chain is allowing more lateral movement then it had before.

What say ye Supedukers?