How do I replace the belt on a Whirlpool Duet GEW9200LW1
Here are your parts
http://www.appliancepartspros.com/partsearch/model.aspx?model_id=504166
The following will help with your repair.
http://appliancedigest.com/index.php?/files/file/325-l-69-whirlpool-duet-gas-electric-dryers-service-manual/
You will have to join the site but it is free and has many manuals for the appliance DIYer.