It is common for these switches to fail. Have try to replace it yet?
It appears the whole handle will need to be replaced, do you have the serial number?
It has several versions for the different options.
I also see it has been updated a couple of time too.
Integrated Toolcarrier: IT14G (S/N: FWL1-UP; KZN1-UP; 1WN1-UP)
Description of Change: An improved Modular Handle Group is now used on the above listed machines. These new Modular Handle Groups feature better design of mechanical switches in order to improve durability and reliability.
Adaptable To: The improvements were effective with the manufacturer's date code of 0501 (2005, week1). The affected parts are listed below:
Is your machine listed here?
I just found a guide for your problem, see if this will help you pin point the problem.
Symptom (Will NOT Go Into Gear) Neutral Lamp Flashing.
The transmission control will NOT engage the direction solenoids if the parking brake is ENGAGED. When the parking brake input (connector contact 42) is open the parking brake is ENGAGED. When the parking brake input (connector contact 42) is grounded the parking brake is DISENGAGED.
1. CHECK PARKING BRAKE - Check to see if the parking brake is DISENGAGED and the parking brake lamp is ON.
2. Reapply parking brake. Measure voltage between the normally open (NO) pin (765-BR) and the common pin (201-BK). Voltage should measure 9.5V±0.5.
3. Check parking brake switch operation.
4. CHECK FNR SWITCH - See FNR switch test charts located earlier in this text.
5. CHECK DIRECTION SOLENOIDS - Disconnect the direction solenoid connector. There is one four pin connector for both solenoids. The solenoids are located on the hystat pump body. Measure the voltage (on the harness) between pins 1 and 2 (Forward). The voltage should be 4.5V±0.5. Measure the voltage (on the harness) between pins 3 and 4 (Reverse). The voltage should be 4.5V±0.5.
6. CHECK DIRECTION SOLENOID RESISTANCE - Measure between pins 1 and 2 (Forward). The resistance should be 5 ± 2 ohms. Measure between pins 3 and 4 (Reverse). The resistance should be 5 ± 2 ohms.
7. NOTE: If the FNR indicator lamps that light up the direction arrows and neutral lamp (located on the right side of the dash) are shorted to ground. The control may think the direction solenoids are shorted. These lamps are in parallel with the solenoids. The chance of this occurring is very rare. This short would have to sink in excess of 4.5A. This has NOT occurred in testing or in the field.
Here is the test chart list in the test.
The connector is below the control lever covers and is connected to the ecm controller.
If ANY fault occurs with the control module or system components the Neutral Lamp (right side of steering console) will flash.
NOTE: The transmission control is unlikely to fail. Access to the transmission control and connector is difficult. This troubleshooting guide is written to minimize accessing the transmission control and connector as much as possible.
NOTE: Avoid removing the TOP of the right side console. It is easy to remove but DIFFICULT to install. If you remove the top take the time to label the nine (9) connectors that must be removed from the switches to gain access to the transmission control.