Some machines test the motor rotation on power up and if this is abnormal they throw a wobbler. Check out the carbon brushes in the motor. Theyre graphite blocks which transfer mains power to the copper segments of the motor - located at the other end of the motor from the drive pulley. Theyre probably worn down.
Also check valve inlet filters, pressure switch, pump and wash filter.
Check out this site for info: www.2ndwave.co.uk/manual.html
dan, February 2008