Hi Keith,
Got back to it after a while when a scrapper turned up. Problem as you suggested was MCZ3001, and changed the 2SK2640 Fets for luck.
Thanks again - Chris.
PS - Reason for long repair delay was the cost of the chip - some 20 pounds plus, well I'm a cheapskate, and don't want shelves full of loss leaders. Original cust had bought a new Sony 'Lite' after a couple of days anyway, as they do. Xmas is near, sure to shift it, It's a Sony, and awful heavy.