Dryer won't stay running and smells like burning

Dryer won't stay running and smells like burning

I push the button on my kenmore 80 series dryer dryer and it will stay on while I am pushing it but quits after 30 sec and smells like a burning smell. We took off the back a nd cleaned it and replaced the door latch because it was bad but now I'm not sure what to replace.

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