Were the SO 239 is mounted with the wire coming out and going to the matching ring, cover that whole area with a good RTV sealant.
Most likely ( especially if it has not rained in a while) dirty water is shorting the connector.
Have a look at the attached images.
This is for the I10K antenna, but I am just using them to show what I am talking about.
First one shows the SO 239 connector with the braid attached.
Think of this as the connector on the workman.
In the next picture of the tuning set up if you look close, you will see that the connector and braid is covered with Black RTV sealant.
Also if you did not use coax seal around the PL259/SO239 connection, you could have water intrusion into the cable.
These connectors are not water tight.
This is were a good, small dummy load comes in handy.
Remove the cable at the connector, attach the Dummy load, and read SWR.
If it is good, look elsewhere for the problem.
73
Jeff