Rhodes Chroma Polaris

over the past 3 weeks my polaris has had an odd memory loss problem. While playing a song, particularly a section on the bass notes, the keyboard just stopped making  sound. and wouldnt respond to pushbuttons, I restarted the polaris  and  changing to other programs  showed that all the sounds had changed and even the 6 voices didnt play sounding  the same-- autotune would bring the voices back, but i had to reload the memory from the cassette to get the sounds back corectly .  this has now happenned  3 times--- but with plenty of normal operation in between.  the only thing I can think of as a cause could be related to how  a couple months ago i did a memory chip upgrade---with new chips from digikey--- every thing was fine it seemed---but in pulling the old chips i had to pull pretty hard and i definetly was flexing the PC board. could i have broken some traces or solder joints?? and that i could loose battery power for a split second thus screwing up the memory?  im trying to figure this one out,  any ideas?  The odd thing is the inconsistancy , but i think i was playing the same song with a rocking bass part on the low octave black keys when it just died---perhaps vibrating it.  does this make sense?