Jim, good luck - any worn parts anywhere and the Roomba is toast. I assume you've called IRobot customer support? They may trade your Roomba for a used refurbished one for half the cost of a new one.
Check the wheel treads for wear, the thingy that pops out when you pull the brushes, etc. If any of these parts are worn, your Roomba won't work. IRobot will send you a new part, but it may take up to 6-8 months, and may not solve your problem.
Roomba is a great idea that's badly executed. Mine died after 6 months of use, and didn't respond to any repair attempts. They need to make the moving parts out of something besides plastic.
Hays
July 2005