Hi E/P,
Never thought of that solution - eventually fitted a PhiHong PSA066-120H from a scrapper - it too has single 12v output and was of similar size - Thanks - Chris.
Hi Doug - Ordered a small cheap heap of SG6841SZ as keen to know fault for next time - sure there'll be more of 'em.
PS - SG6841SZ did the biz, so now have a spare.