I've been having problems connecting the hydraulic hoses for the FEL on my 1528. Most connections are made easily but there always seems to be one stubborn connector. Not sure yet if it's the same one every time. I've determine the problem to be the check valve in the connector. Unlike the check valve on the other connectors, the check valve on the stubborn connector does not depress. Therefore, the connector will not seat fully and make the proper connection. Any suggestions on how to resolve this problem?