Thanks for the quick replies. I agree that the PX-350 is both capable and presents some learnability issues because it uses some buttons for more than one function. My Casio PX-3 and WK-6600 have more buttons relative to their number of functions, so they have fewer "moded" (the same button does more than one function, depending on the mode it is in) button sequences. That makes it easier to figure out on the PX-3 and the WK-6600 which buttons to use for specific functions. Anyway, yesterday I tried saving tones in registrations again and this time had no problem at all just saving tones without at the same time saving rhythms or accompaniments. I don't yet know why I had problems one day and not another. Perhaps I had rhythm or accompaniment buttons lit the first time I tried it, as one reply to my prior note has suggested. A follow-on issue is that, while the PX-3 manual explicitly says that users can move through registration banks by pressing the up and down buttons, the PX-350 manual only mentions moving through the banks by repeatedly pressing the Bank button. Hmm, There are 24 banks on the PX-350 and the only way to move through the banks is to go in one direction (from bank 1 to 24) only? Hmmm, I have used a PX-3 for several years on gigs and was able to move back and forth between the two banks that held my favorite keyboard sounds. Now to go between 3-4 banks of favorite tones I would need to go through many banks, most of which contain nothing, and in one direction only? That probably is not correct, but the manual implies that that is what would be required. It would have cost very little to have a technical writer add a clarifying sentence to the manual. Still, I think that the Casio keyboards do a great job overall (light weight, excellent sounds, excellent action, etc.), which is why I have owned several different models over the years.