I purchased a Maverick Et73 a few months ago and have used it about 10 times for low and slows. The meat probe seems to work fine, but the grate probe seems to be malfunctioning. The grate probe will register a reasonable (and likely accurate temperature) for the first 2 or 3 hours of the cook, but after that it begins to report a steadily rising temperature eventually leading to grate temperatures that equal and then exceed dome temperatures by 50 or more degrees. I have checked and calibrated all thermometers and checked the grate temperature with multiple instruments. Any one else have similar issues with this product or have any suggestions?