Gaps in chart?

Been a few months since I’ve been able to run the smoker, but set things up last night to run a small catering job I have today for a Christmas party. Everything seems to be working fine in that the controller is keeping the pit temp right and running the blower, but there are now gaps in the chart. Any ideas what that might be?

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Doh! Figured it thermocouple for the pit wasn't plugged all the way in. I guess it may have been shorting or dropping out, etc. Pushed it that last 1/4" and it is rock solid.