IIe faulty RAM ?

["Mark Cummings" <NOTfigjams@primus.com.au>]

I have an extra Platinum IIe International NTSC motherboard that WAS working
and now NOT working.
IIe has known good power supply, and 5.25 controller in slot 6 with a 5.25
drive connected and a 80col/64K card. Except for the motherboard all the
other parts are known good.

These are the symptoms:

1. Power on produces No beep, a display full of random text/or graphics
which appears to be flickering, and the disk fails to boot. All voltages
measured on the motherboard are good.
2. Attempt to Ctrl-Reset freezes display until RESET is released, but then
returns to previous condition but usually with a slightly different screen
of garbage.
3. Attempt at Ctrl-OA-Reset, is pretty similar to Reset, although
occasionally I get a noise from the speaker or the disk light goes on
(forever, until Reset again). I guess this is just the drive motor I/O
location getting some garbage.
4. Attempt at Ctrl-Option-Reset gets treated similarly, occasionally the
80-col display comes on, or a graphics page with similar flickering
graphics.
5. Attempt to use freexe spray or my thermonuclear device (hair dryer) has
failed to alter the state of the fault. This was an old trick that I
remember using years ago on a II+.

I have swapped all the socketed IC's out with another identical working
unit, and the result is the same. The chips placed into the other IIe work
fine.

I am suspicious of the soldered in RAM, which is 2 of 41464C-10. Before I go
desoldering, can anyone shed any experience with RAM faults and the
symptoms.

Would the inbuilt diagnostics (Ctrl-Option-Reset) run correctly if the RAM
was faulty, if so how would it display the result, since the text screen is
memory mapped. Also, should it still make any sounds, as this would be
addressed outside of RAM space ?

One thing I have noticed is that there appears to be some message in the
middle of the screen occasionally that looks like R?M something or other,
which I think is a call for help ! :O

Mark