Believe it or not, this is a "new" piece of equipment to me as it is an upgrade from the 712 WISP. Anyways, the 717 I just inherited has the Calibration error of "Top sensor too low" when I attempt to calibrate the seal pak. Does this mean I'll have to replace the whole Seal Pak or is there just a small seal gasket that would suffice? Any advice would be very much appreciated.