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You could try a restart to see if that kicks it back into life:
http://help.fitbit.com/articles/en_US/Help_article/How-do-I-restart-my-tracker/
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Welcome on board @LbLovell! Besides the restart recommended by @SteveH, you may want to switch your heart rate settings from "On" or "Auto" to "Off". Save and syn and then turn it back on save and sync, You can do this from your Account Settings. You can also try to wear it a bit higher than usual. Something like this:
Hope this helps!
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