The Kawai & Teisco Analog Synths Group

I was trying for some time to fix my sx210..At first nothing could be
done.I found after a while that someone had connected wrong some of
the cables..It became operational..but many buttons wouldn't light..
I then found out that one button of the vcf was not in connection(had
broke) so I got it fixed..
Now it's almost in full operation but the only thing I can't do is to
store patches.The only button that isn't functioning is the 
[memory write] and I know it isn't the button itself that has a
problem because I tested it elsewhere and it works. It is the only
button though that has a small chip besides it(is it a chip?it has
only 3 connections-i'm not a technician).
Maybe this chip is not functioning?How can I test it?
I would be very grateful if anyone could tell me.
Thanks,
Christos