Hello Sarah,
Unfortunately I do not have a picture of your model, is this the first time you are using this machine? the only way it will get caught round the tension discs and is if you have gone round the discs twice which is quite common, or you have gone through the take up lever then through the discs, if you have used the machine before and it was sewing okay it must be something you are doing wrong, the tension assembly itself starting from the front and bearing in mind I cannot picture the model would start off as a round thumb screw, numbered dial, small pronged washer,cone spring, 2 tension discs,small back plate, if it is possible for you to e-mail a photo of your machine if you get stuck it would help, drivewithken@blueyonder.co.uk
Ken
drivewithken@blueyonder.co.uk, October 2007