So after looking at the diagram (http://servicenet.dewalt.com/Products/GetDocument?docName=EA022468.tif&docPath=http%3A%2F%2Fdocuments.dewalt.com%2Fdocuments%2FEnglish%2FExploded%2520Art%2FEA022468.png&productId=22538&productType=7605&documentId=21151) I'm thinking either a sprocket, #83, or the chain, #101. Also, check the speed selector lever. If it's not fully engaged to 1 or 2, the rollers won't spin. Did you happen to change the speed while the planer was off?