Thanks to Ken for sorting it out for me.  

Turns out that Beaky was right on the money, faulty RAM was the main problem.... it also needed a new U5 to restore the digital volume control function which was stuck at full on.

BTW If you need to replace the digital pot. U5, which is a Xicor X9503P (hard to find in Australia and expensive) you can use a X9C503P Intersil chip which is available for around $4.50 including courier delivery from

http://australia.rs-online.com/web/p/products/642-4137/