Tektronix TDS 754D aqcuisition board fails (channel 1)

[okw]

I get a "FAIL ++ Aqcuisition" at boot. I let the scope warm up, and tried to run the calibration. It fails. I've attached the error log.
What could this point to?
In the picture attached, I feel channel 1 with 10MHz, 400mVpp.
Ch2/3/4 seems good (although it intermittently shows "histogram unstable", could be because I fed it with a low amplitude signal?).

[TERRA Operative]

Looks like a faulty acquisition RAM problem. I had the same thing with my TDS794D.
The periodic nature of the spikes, and that they are at the same level indicates that some RAM chips have stuck bits.

I ended up removing the RAM chips one by one from the affected channel in my scope and testing them in my Retro Chip Tester Pro to find the issue. I found a number of bad chips that were replaced with chips harvested from another faulty acquisition board (pulled from a scope that was physically smashed).
Just be aware that the RAM channels don't line up with the input jacks, they are in a different sequence. I can't remember the actual sequence though.

I have a bunch of spare tested good RAM chips I can send cheap if you need them (Post an image of them so I can check if they match mine)

[okw]

Thanks for your reply. Seems my CPU board has AS7C256-15JC and 6 of them, and the acquisition board has "71024 S12TY M9921M" and 32 of them (4 banks of .
I guess it's the latter I need to replace. And only the ones associated with channel 1?

[TERRA Operative]

Yep, that's correct, just the faulty RAM chips for channel 1 on the acquisition board.