Kubota ST30 3 point linkage failure

[mogsareus]

I have an 800hr ST30 which I have had for around 20hrs.
After using it for 2 hrs today with a 1.3M fail mower I found, just as I returned to the workshop, that the linkage dropped and cannot be raised.
I have clean out the hydraulic filter, which did have contamination, but not enough to block it as the hydraulic outputs still pressurised.
The machine is in nice condition, but has been lying for some time prior to my purchase.
I can only think of accessing the actuating valve to see if the linkage has come adrift (although it doesn't feel as though it has) or that I have contamination in the valve that is holding it open.
Advice/experience would be welcome.

 

[J_J]

Put a hyd gage in your hyd system, and the readings should lead you in the right directions.

 

[mogsareus]

Many thanks for your reply J_J.
This proved to be a simple one - a broken link between the hydraulic valve and the 3 point linkage arm casting.
Cause. The pivot in the linkage casting seized, the 8mm round bar was then bent too and fro as the linkage was operated.
In carrying out the work to identify the problem - in a machine with a factory cab on it - I have made a simple modification to allow the panels below the tool locker to be removed without taking the cab off - details available if anyone is interested.