they are repairable. Remove guage and capillary tube and nut that attaches the
bulb to the engine. Send the whole mess out for repair. Not sure who else
does it but I just had one repaired by Air Parts of Lockhaven. You can find
them in the trade a plane. They will attach a new tube to your gauge and
recalibrate it. Last one I had done cost me about 150.
Mark