Sperry Marine VMFT/BME radar / ecdis operator station uses trackball to operate the system.
Many times when the trackball was heavily used by ship crew to activate or enable/disable a function, it was pushed many times until the MTBF(mean time between failure) has reached the maximum life span. This happens normally on the left push button due to left push button by nature is use more heavily compare to right push button. To replace the push button, ship owner can order from Sperry Marine the push button switch kit - T65900701-1