Kubota KX161 Excavator Thumb Issue

[rust buster]

I have a Kubota KX161-3ST that has an odd thumb issue, and has since I've owned it. Machine has 1900 hours and the thumb control is a thumb wheel on the right joystick. The activate the thumb, you have to thumb all the way to the right ad HOLD it. If you let go, it quickly releases the hold. And if you thumb to release, it will release all the way. The complete joystick assembly is $1030 so that is my least desired option. Just the stick is about $400. Anyone had this issue and do you think it is an electronic problem with the thumbwheel itself or do you think there are hydraulics involved? Is the thumbwheel serviceable and or cleanable if the contacts are bad?
Any info is greatly appreciated.
Thank you
-Tim

 

[heymccall]

On my Takeuchi machines, there is a ball valve to turn, one way for hammer, other way for thumb.
Looking at parts manual, I don't see a ball valve on there, though.

 

[Midnightmoon]

Test voltage at aux spool to test thumb wheel is working properly. Could be sticking spool. If theres a valve for breaker use it would be by the hyd tank fill. That may be the issue

 

[rust buster]

Thank you. Going down the "sticking spool" theory, is there a tried and true way to unstick it? I see there are basically two culprits...the joystick unit or the proportional valve (auxiliary spool)...

 

[rust buster]

I found a long process in the shop manual to "set up the thumbwheel control." If any of the components were replaced prior to my ownership, and they did not run through this procedure, that could be the cause. That would be the ideal situation and cheap!

 

[rust buster]

Well I replaced the joystick and did not change anything, so now I'm singularly focused on the spool. Anyone had luck messing with that?

 

[rust buster]

Only two things left that it could be. The Solenoid valve which translates the electrical input to hydraulic output, and the actual spool.