I have connected and reconnected at the grapple and also at the rear where the hoses connect at the back. I can hear the valve clicking when I depress the thumb switch each way but no operation. Call service and they said to blow compressor air into the quick connect at the rear after disconnecting each of the two hoses. Said there is a screen that gets clogged if sitting along time. It’s been three months since I have used this function. I did this to no avail. Any suggestions?