Hi Malcolm
The speed control circuit board for that machine is now obsolete, the only option is to upgrade the motor with the new speed control system. This could be fitted by some one with some knowledge. You will need I think 4 or 5 new parts for the conversion and they would cost about £75, if you change the machine that would cost up to £249!!
If you need further help just call me on 01273 734424
Jason (Kenwood Service Agent)
Jason (KENWOOD SERVICE AGENT), October 2008