If you have ever struggled with the 100m tether reel when winding the tether in or out and having the the topside module on the side of the reel fall off or the tether catch on things then the following modification might help.
To complete this modification, you will need to remove the tether itself, the side cover plate, the grommet from the hub penetration hole and the unused cable clamp.
You will then need to make the hub penetration hole a bit larger for the tether connector to pass through. I used a small barrel grinder on a hand held drill.
You will then need to make a small slotted hole in the cover plate to allow the tether to exit the hub area.
After adjusting the length of the tether tail to suit the location of the topside module, secure it to the hub with some tape.
You can then secure the topside module to the side of the tether reel with some velcro (in addition to the elastic strap).