Can you replace a broken wheel on your robot vacuum?

I'd like a household robot to outlast one broken wheel. There is something lovely about a machine going back to its ordinary job after one small part changes. iRobot's existing support guide lists replaceable left and right wheel modules, a cleaning head, battery and other parts for Roomba 500, 600, 700, 800 and 900 series. It says to buy the module specific to the robot's series. That's a useful example of repairable design, not a claim about every Roomba or every robot vacuum. If yours stops moving properly, I'd look up its exact model and the manufacturer's troubleshooting guidance before deciding it needs a new wheel—or replacing the whole cleaner. A symptom isn't a diagnosis. If a replacement is needed, check whether the correct part is actually available, what it costs and who can fit it. A support page describing a part doesn't establish today's stock. For the next robot I buy, I'd want to find its repair instructions and spare-parts listings before watching another obstacle-course demo. Keeping an otherwise useful machine working would matter more to me than a clever new trick. Which ordinary failure would you want to be able to fix without retiring yours?