Than someone will need to do some further checking. The venting and the heater element would be high on the list.
I might also suggest a different technician/service company next time. One that provides factory service for the appliance brand in question is usually a good choice even though they possibly will not the cheapest option.
LINK >
Home Service: Technician Pros and Cons
JMO
Dan O.
www.Appliance411.com
The Appliance Information Site
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