Someone correct me if I am wrong but if that crank is welded, its not going to move by hitting it with a hammer, might make it worse. By the way, .04" of runnout is a LOT, I'm guessing you meant .004"? That is still 2x stock spec, though. Cranks are pretty cheap from SBT..
I’ll try the hammer and if I can’t get it to zero or max 0.001 then I’ll call it quits. If I knew the crank was screwed, I would have just bought JetManiac’s ported engines. It would have been the same price as building one