Virtually all catastrophic dryer fires start in the dryer vent, not inside the dryer itself. This is because most vents are poorly constructed and get filled with flammable dryer lint resulting in a disease we professional appliantologists call, venterialsclorosis. See this post for more on that:

http://fixitnow.com/wp/2006/12/26/dryer-venting-diseases-venterialsclorosis/

If the dryer vent is made using that cheap, collapsible plastic hose, you’re really asking for trouble!

For more information on how to make a proper, safe dryer vent, see this post:

http://fixitnow.com/wp/2003/10/15/appliance-tip-of-the-day-the-ultimate-dryer-venting-guide/

To learn more about your dryer or to order parts, come ye hither: http://www.repairclinic.com/Dryer-Repair-Help