Discussion about the Korg PolySix synthesizer

Hi,I can't save correctly a patch on my PolySix.I program a sound and I press the red write button which starts to blinking.After, I select a program (for example 1 ) and the sound is saved.Now, if I press again 1, the sound partially changes (the filter settings)Sounds like I can store in memory only some settings.Can be a faulty RAM issue? I have already fixed the acid  leakage.Any suggestion is very appreciated.Thanks.Giorgio.