Dave,
I just spoke with AJ on the phone because I don't know of an accomp. lock on Ketron products. We discussed your post and he realizes you want to lock the accomp. parts out and not just lock the bass sound and other sounds from changing. The Ketron X1 and SD1 can lock the bass sound and the left hand sound, but there is no lock to hold all the other chord sounds and parts on and off. You can turn all the volume setting off and these will hold, but if you turn down the bass volume, there will be no bass sound. On the X1 you have to turn off a lot of volume tracks and this can get messy.
However, the new XD9 has a feature called "BASSIST". If you turn this feature on, and use the feature called "BASS LOCK", you can switch to any style and have only the beat change, but the bass sound and the ability to only play left hand bass with whatever you want on the right hand, say pianl/strings will remain. Chord recognition goes automatically to the right hand, so if you wish to hear an orchestra being played from right hand chords this works, or you can mute the chord volumes, which is on one button and it will hold for every style you select.
Sorry this doen't help the PA80, but for anyone playing UD's style, would like this new feature on the XD9, XD3 and Vega.
George Kaye
Kaye's Music Scene
Reseda, California