The problem is going to be the timer itself. They are about $65.00. They are available here.
For a breakdown of the door assembly go here and click on view diagram in the upper right of the page.
Im afraid that there are no outlets that will guarentee that you can return an electronic part. Most will not allow it and those that do always have disclaimers that they can fall back on to disallow the return.
Rest assured that the timer is the problem. There is nothing else that is going to cause this problem.