I think I have located a possible fault.
Sometimes the machine ignores the 'down' limit switch that stops the blade, and the machine continues down.
If I manually operate the limit switch and it is ignored, I can hear the solenoid on the hydraulics clicking as I operate the switch, so the limit switch circuit is working correctly.
There are two solenoids, one that makes the blade go up, and the other that makes the blade go down.
Is this just switching a valve in the hydraulics???
Could the valve be sticking???

If I fix this fault, can the limit switches be replaced with an optical switch or a proximity switch???
So improving the consistancy?

Andy