1976 MZ ISDT replica

easy job monday night, drop the new chain on and adjust it to the correct tension, not in the loveless shed, chain on, split link fitted and adjusted, spin back wheel and there's a definate click, click, click as the chain goes through it's cycle, check wheel alignment and we are less than a mil out, is the chain 'picking up' on the heavy grease on the new chain?, clean it off with white spirit, no difference, take off front sprocket, drill out a 16mm washer to space it over a mil and a half, no use, the sprocket is sleeved to make a seal, run out of ideas so re-fit front sprocket and chain and the 'click' disappears, weird, anyway like these vintage hilclimbers and the late, great, roy castle said 'dedication, dedication, dedication's what you need.....'