I had the same issue, the "Main Gear" which is the largest gear with a "1" molded on the flat side, it has 37 teeth on the large gear and a smaller gear which has 14 teeth and a 6 point hex molded into it to attach to the cutting blades. I called Fellowes and was told that this gear is no longer available, so I made one, and it works great.
If anyone else is in need of this gear for a Fellowes DM65C I will make them one for $15 usd plus shipping, if you have the same gear that is an issue email me at brianscx@comcast.net and I will provide further information.
If you have a different gear that is broken I may be able to make you one but you would have to send me the broken gear so I can mold a new one. The cost for this would be more then the gear itself because of the expense in building a mold before molding the new part, probably around $35 plus shipping
brianscx@comcast.net, August 2007