From my limited experience with my
factory refurbished ST5000, I know that the wire connectors, into the back
of the control head can create problems. Might be ok when you insert the
connector but later when you push the head back into it's mount location,
they can bend and cause a strain on the connection.

Also the OEM connector lugs were gold plated as are the connectors in the
back of the control head. I never had enough for the installation and ended
up using some standard connectors which I had difficulty getting onto the
male connectors in the back. Right size, but had to spring them open
slightly, just a bit, so they would slide over the males.

My point, check that your connections are corrosion free and are making a
good snug fit in the back and they are still tight after you install the
control had and secure the wiring.

Unfortunately, in my case, once ST5000 installation was completed, it only
ran long enough to fail in the middle of sea trials and calibration. Tooooo!
expensive to have it serviced by Raymarine. I gather from the online price
list, it would be a flat rate of about $250 and all I would, most likely,
get is another refurbished unit.

Sorry I can't be of more help. Mostly expressing my own frustrations.

Steve
s/v Good Intentions (reverted back to my ole AH3000)