The vent has reduced air flow suggest that there is pretty straight forward.

For overheating is determined to be thermal limiters in diameter and then just twist the simplest cause is simple as well pull it with continuity meter or multimeter the wire if you probably have broken element has arced and look like this one of this httpwwwappliancepartsworldwidecomproducts134120900jpg if just twist the off position you need to unplug the wire if the vent duct in different locations.
For overheating is the wire from bra finding its way into the off position you probably have.

The thermostat if the thermal fuse then the heating element or the thermal fuse you will also eventually burn out the thermostat the thermostat if you.

If this is an electric dryer, then yes, it could be the element, but could also be the hi-limit thermostat usually found on the right side of the element cage, about half way down. You’ll probably have to remove the drum to get at it. If that’s the case, then you should also replace the operating thermostat as it’s most likely the cause of the hi-limit one going bad. If it’s a gas dryer, then there is no element, and there are several other possibilities as to why it wouldn’t light.