Product review (5 stars): A new Igniter solved the problem.
Our GE oven started to act up with it coming up to temperature very slowly.  Researching the problem on-line pointed to a failing igniter, so I ordered one.  It came quickly and was a perfect match for the one in the oven, including the connector.  However, they even included some ceramic wire nuts just in case.  The repair took maybe 20 minutes with the help of an on-line guide.  (The trick is to know how to remove the oven bottom plate.)  Since a service call for this repair can be very expensive, this is certainly something a handyman should try.  Thank you!