I'm by no means the expert... Dale is the man with this stuff.
The DRAM test is just an idea. (sorry, it's DRAM not RAM)
Look for U26 (that has the least significant bit)
There should be 4 of these in a row... I think in order of priority.
So, if you move them around & the NOISE goes up or down with the movement of the IC's, then this is part of your problem.
Yes, finding these IC's is not easy but what you can do is move the "Noisy" one to the "least significant bit = U26"
This worked for me until I found a replacement.
BE CAREFUL!!! Make SURE you're GROUNDED & Discharged = STATIC!!!
Wrap a bare wire around your arm if you have to, then to something else well grounded.
Power down & UN-PLUG the unit from the wall.
Any further help you need will have to come from Dale.
This is what he told me to try, I'm just sharing it.
Good luck