I have an old Apple IIc I am restoring. When I turn off the power, the memory does not clear for more than a minute. That is, I can turn it back on, and be back where I left it. I even tried unplugging the brick from the back of the IIc, but to no effect. So whatever is happening must be internal. Is this a known issue? I guess that it might be a poor capacitor, but is there some other component meant to drain the caps that should be checked?