We bought a Thermador cook n vent range in 2001 or 2002. So many parts are discontinued! The other day, the knob for my most-used burner broke, and I can't glue it. The part has been discontinued (it's number 400415364) and Thermador says there is no substitute part. Oy. So what can I do? Does anyone know a super good parts source that can find things others can't?

Thanks in advance for your help, oh wise ones!