The leads from the wires to the element burned out in mine.
I replaced the wire leads, pushed them onto the element and the unit is working again.
Everything is visible once you remove the back on mine.
Masterbuilt has changed the front door since mine was purchased. They may have changed some internal parts also.
When i tried to buy parts i was told they were not available and to purchase another unit. That is what i expect when i buy ***** ******* ****. I would compare the quality of masterbuilt smokers with tools from harbor freight.
Your mileage may vary.
IF i had the $$ i would replace it with a cookshack or fec.