I didn’t know this, but there’s a known issue with the timing of a batch of Rockwell 6502 CPUs manufactured in the very last weeks of 1982 (date code 8250 or higher). Apparently, Atari had found a workaround using a 470 Ohm resistor and a 100 pf capacitor.
Trigger warning: Not a computer. (Atari 5200)
The AtariAge thread on the subject, including a download link to the Atari Tech Tip may be found here: https://atariage.com/forums/topic/290185-can-anyone-help-me-fix-grapthic-issue-on-the-atarimax-sd5200/
Maybe this can be generalized from the schematics and may rescue a 6502 system behaving somewhat erratically?