We have a LabelJet 2300 which is not functioning properly. The air blast to apply the label operates when the labeler is first turned on, then after several minutes (15-20) the air blast is not actuated. If you turn the controller off and restart, the air blast will operate for a minute or so and then stop again. We have replaced the product photoelectric sensor and have ordered new air solenoids. I inspected the electronics in the controller and noticed that one adjustable POT has been hot enough to burn the adjustable plastic part off. Any thoughts?