Hi,
I found this on another fix it site.
"The problem is that the load resistor has failed which is common. You would probably need to replace the capacitor as well as that usually fails when the resistor fails. You can replace the capacitor with a 0.1 microfarad 250 - 275V mains capacitor instead of the old electrolytic type. The load resistors are hard to get (hence expensive - about 12 pounds in the UK) I have a few spares. If you want I can supply the 3 components that make up the speed control for A$20 plus postage. These should then last for years. email: wilsonsrus@bigpond.com Note that the KM300 is a different system to the A701A "
The load resistor he mentions I think is 450 ohms, this was from another site.
Hope it helps.
Jon Hassler-Hurst
September 2008