I have an Ironman Elliptical model 420e. While I was working out I noticed that all of a sudden that the calories and watts are not changing. I unplugged it and both watts and cals stay at 0. however the time, pulse is still changing as its supposed to. I still feel the resistance when I move the pedals. Is there anything I can do or buy for it? Any help would be appreciated. Thank you in advance.