ELECTRIC TRANSFER CASE

I have been working on an electric transfer case that someone else has done work on before. The problem i have is it engages 4x4 and 4x4 low, but won't stay in low; it jumps out after 5 seconds. All the internals look fine apart from a bit of chain play, so i made a nylon guide for it. My question is regarding the shift motor. I notice that it has spring tension, so how would I know if it is set right? Is it centred, or is it more to one end, ie, forced back or forced forward? Also, are the ball bearings in the position sensors the same size any helpm would be great thaqnks Chris 

Is it actually jumping out under tension or is it retracting itself? The low range sensor may not be working. If it doesn't detect that it's in low range when it thinks it is,  I think it retracts itself? 

I have not noticed any spring tension in mine, sure that it is OK inside?
Mine has always found their actuator position after swapping them or after servicing.

Or could be electrical.
Both balls under the switches are the same size from memory.
Switch wires are prone to failure especially when offroading. I have used cable ties and Tec7 to make the wires come more up in the chassi and less exposed.
I have ripped of those wires a few times and when that happens the box usually stops trying to shift and the lamp in the dash blink slow and make beeps when a signal from the switches are missing, and sometimes looses front hub engagement too.