JST/Omori boost gauge

Just wondering if anyone here has had to replace the sensor for their  JST/Omori boost gauge?
 
Mine is reading incorrectly now, the gauge itself does the calibration sweep and then as soon as you start the engine it constantly sits at 30psi occasionally doping to 25 then back to 30. I have connected a vacuum pump to the sensor and it will not drop below 30psi so it seems to me the sensor is faulty and so far I have not found anyone selling the sensor on its own so I am curious if anyone else has replaced the sensor with a different sensor with any success.