When you say not working is it making a noise but not spinning or is it just completey dead?
Ok if the power supply is fine and the locking handle on the top is working an locking into place then its either the switch unit or the motor at the bottom.
What you need to do is tip the spinner upside down and remove the bottom cover.
From there you will see the switch unit it will have the mains cable going in to it. Check the locking bar is going into it and no wires have come lose.
If you have a multimeter you can check the switching unit and see if its woking by testing continuity across the switch. If that's ok then the motor is the fault here.
But as this is an older model 1999 quite a few of the parts are now obsolete. The motor is listed as obsolete so if that's at fault it cannot be repaired.
But just check for any lose wires at the bottom as you never know.
If you need anymore info just get back to me.