An 8 bit ROM based sample machine with wavetable joystick control and a cool AM routing. All cheap digital design. Amazing machine for it's day in terms of features/price. Came in Rack and module/table top version as well as 61 key keyboard. The K1-II just adds fx and some kind of drum set organizer as I recall.
I haven't really seen any issues with these but from looking over one of my modules I imaging solder problems have happened. Even fixing that I still have a pop when envelopes decay all the way. My other one doesn't seem to do it. Annoying!
Most of the parts are going to be pretty hard to find I'd think on these and they're probably available too cheap to worry much about it. :-)