Vintage Synth Repair

My Prophet 5 had an issue where the LED's would occasionally flicker
slightly and introduce a glitch noise into the audio output.  I've
since replaced all  power supply caps (tantalums replaced with
electrolytics) and the LM337 voltage regulator.  After some initial
tests it seems to have remedied the glitch noise problem (even though
the LED's will flicker a bit when adjusting the FILTER CUTOFF
pot...?), BUT (isn't there always a 'but'?!) a new issue has
manifested.  My Prophet is a rev 3.3 with MIDI.  When in preset mode
on any patch ending in the number 8, some LED's on unused buttons
flicker on and off, the numbers on the panel will scramble a bit, and
occasionally, the synth will skip into TUNE mode.  The problem doesn't
happen when I press the PRESET button to take it to panel mode nor
when the patch number ends in anything other than 8.  Is this a RAM
(6508 CMOS) problem?  Anyone dealt with this before?