There are a number of potential causes.
This is how I go about working the problem.
1st I check to see if it is an electrical or hydraulic problem. This can be determined by operating the valve manually.
There is a small round brass rod at the end of both sides of the valve where the solenoid is located. The solenoid is held in place with a plastic nut and through the hole of this plastic nut the brass rod can be seen. It is indented and a small phillips head screw driver can be used to put this rod. Crank up the tractor and let it run in idle. Push this brass rod in. It will go easy about 1/2" then it will be harder to push for about 1/4". This remaining 1/4" movement operates the valve manually. Do this on both sides (one side at a time). If your attachment works then the hydraulics are fine and there is a issue with the electrical side. If it does not work the there is a issue with the hydraulic side.
ELECTRICAL:
1 - Check the switch, which you have done.
2 - There are two small screws that hold the terminal block on. (plastic piece with two wires coming out on top of the valve). Make sure the two screws are tightened. These screws make the connection to ground the valve to the tractor.
3 - A solenoid may be bad but this is extremely rare.
4 - The connectors inside the terminal block may not be connecting to the 2 post on the solenoid. Again extremely rare.
HYDRAULIC
1 - The quick connects may not be completely connected. In your case this is not the issue since you are getting flow in one direction.
2 - The quick connects could be bad and either act like a check valve or completely block flow in both directions.
3 - The valve could be sticking however when it is operated manually this will unstick the valve.
4 - It is Possible that the "P" and "T" hoses are connected backward. Make sure that the flow of your hydraulic fluid is from the power beyond port of your loader valve into the "P" port of the W. R. Long valve.
Hope this helps.
Nelson
W.R.Long Inc.
I'll call WR Long in the morning, but I thought I might get a quick answer here first.
I've installed a WR Long 3rd function electric over hydraulic valve kit on my Kubota MX5100, but the solenoid kicks in only one direction. Press the rocker thumbswitch in one direction: CLICK! Press it in the other direction: nada.
Opened up the switch and swapped the connections: same behavior, different switch direction.
Swapped the wires at the splices down near the solenoid: same behavior.
I guess at this point I need to know if the solenoid *should* kick when the thumbswitch is pressed in either direction.
Thanks,
Jay