HI Ellen.
Firstly get a good handyman/DIYer. Then get the oven model number off the plate probably fixed to the rear of the oven. This will involve removing the oven from the housing. This also helps stage 2 which is to replace the motor once you have the model number.
Go online to someone like ESpares identify the motor, see if the cost is justified against a new cooker. Order same and have handyman fit it. Hump the oven back into the unit, test it and you're good to go. You may need a suitable height table to slide the oven onto from the housing if its worktop height.
Isolate your electrics before starting the job.
Tim, November 2011
