Im taking it the hinge unit has failed has it?
This is what used to always fail on these when you got this fault. The bad news is this cannot be repaired as the parts for it are long obsolete . So any stock suppliers had would be long gone by now.
But if its just the spring thats failed then you can try and remove it and try and match it up with another spring if you are able to find one.
To access the springs you need to pull the oven out and remove the side panels. From there you will see the spring going from the hinge to the back of the oven. Remove this and try and match the spring up as the one listed on this is agai obsolete now.
Sorry its not good news but nearly all the parts on this oven are now obsolete so repairs are not usually down on these anymore.
If you need anymore info just get back to me.