Hi Joan.
You may regret selling the KN7 but they are fetching quite good prices on ebay at the moment.
I have still the CD you sent me when I got my first KN7 in 2002. I changed for a Tyros2 in 2005+ but have now gone back to the KN7 which is still more than a match for the Tyros.
Why not get a typist chair to use when playing it will help support your back?

regards
Peter B