Here to change sensor and inspect the warping on the plastic of the boiler. Replaced sensor and turned boiler on. Preform co test in the cabinet of the boiler. Over 200 ppm co. Removed the cover of the heat exchanger to inspect the interior of the boiler. Found the cover plate gasket blown out. Need to order new cover plate gasket and brought back cover for Jamie to inspect for warping caused by the excess heat going through. Will need to get back ASAP to get boiler running. Heat exchanger should be vacuumed out when we come back. We siliconed around the cover for a temporary fix. Did a test fire of boiler to ensure it will fire when the silicone dries. Customer was told they should not start boiler till 8 or 9 tonight.