Dryer vents are the number one cause of Dryer failure.
Have you ever put your hand over the end of a blow dryer?
It causes the element to glow bright and if your lucky it will click off on a safety device before breaking the element or burning your hand.
This is the best way to describe your dryer. The vent gets clogged ( its like putting your hand on a blow dryer) . The dryer can only run like this a short time before it fails and needs repair most likely the element or safety switches.
Keep your vent cleaned. I also offer dryer vent service and its discounted with a paid dryer service call.