David,
Don is correct about joining the Solton Club. It is hosted by Bob Hughes and there are hundreds of Solton users in this group.
To answer a couple of quick questions......
the jump feature allows you, when turned on, to hit the fill in 1 or 2 button and automatically advances you to the next variation (fill 1) or to the previous variation (fill 2) or if you hit fill 3 it stays right where you left it. Also, when jump is on, you will only get intro's and never get an ending when the jump is "on". This is useful for musicians who like to use intro's to chain styles together. You must turn off the jump feature before hitting the intro/ending button if you want an ending.
Registrations are where you select the style, sounds, effects, etc. you would like to store and by selecting a registration bank and number you are calling up everything you need to play the keyboard in a style and tempo and sound set you like.
I think there is a way to turn on sustain, but I haven't had an MS100 in my store for about 6 years so I can't remember.
I don't know if there is any online manuals available, but you should be able to get one from the distributor in your country.
Enjoy,
George Kaye
Kaye's Music Scene
Reseda, California