I can't speak for the EX-10, but I once owned an EX-1 and while I agree that the quality of KO Propo radios are top notch, I experienced a failed potentimeter on my EX-1 as well, perhaps things may change as potentiometers are improved with contact-less designs, but until then, all traditional potentimeters will fail eventually, regardless of the brand of radio. When you are buying a used radio, one can only guess how much use it has seen, though many of the newer KO radios include an "odometer/timer" for aggregate usage.