This is what I believe to be the most common problem with SG levelling heads. At least it's what I found on 3 heads
so far. Fortunately it's rather easily fixed. See the pictures below of an SG5030 head (click on image for a close up).
As you can see, the shield of the coax is completely broken due to bending back and forth of the cable during normal use.
I took the ferrule from a crimp BNC connector and cut it open so it could be placed over the cable. I used a very thin sawblade
on a Dremel like drill to get the very fine cut.
Stripped off a piece of the outer isolation of the coax.
Placed the ferrule on the cable, pushed it together, soldered it along the
cut edge and then to the original cable fastener.
Then used the crimp tool to crimp it on to the cable shield and finally also
solder it to the shield.
With a little force the original plastic housing that hold the cables and rubber sleeves will slide on the modified cable.
/Håkan H