Hi Ted this is due to contaminated gas you will need to replace the fluid sensor and LPU (Low Pressure Unit)

Part Number: 0105199130
Description: COMPLETE PNUEMATICS UNIT LPU

and the fluid sensor

Part Number: 105190933
Description: FLUID SENSOR

As this is for a mission hospital Stryker may be able to sort out some sort of donation repair, contact your local stryker rep if not let me know and I will see what I can do.

All the best

Nick (Field Service Engineer - Stryker South Pacific)