Vintage Synth Repair

I have a Crumar Trilogy with some problems... 

First of all I need a CEM 3330 and a CEM 3320.
One voice board is dead due to these chips. Maybe also the CEM 3310 is dead, I�m not sure at the moment. Can anybody help?

Next there is a another strange problem:
When I switch on the unit, after appr. 1-2 minutes there is a hum, that can be heard best in the string section and in the synth section. If I only play the organ section I don�t hear it. 

The LFO speed is influencing the hum. Very nice effect... 

If I pull a few of the voice cards, it seems to be, that the hum is lower in volume, and that it is starting after 3-4 minutes after I switched on the machine.

What is the problem here?? PSU? Or anything else?