Instead of going over the hole, why not maybe get something pliable like a short legnth of rubber or vinyl hosing in black, just a bit longer than the oval holes on the tup tube, drill or punch a hole on it so the cable casing could go througn, cut/split it along its legnth and remove a strip of material so you can fold or scroll it and fit it into the TT and then let it open up inside to go against the inner wall of the TT so you will end up covering the open oval hole from the inside. You might have to experiment using different legnths, thickness of tubing for each hole. installing and removing he section of hose from insde the TT should be easy enough by ising a long nosed pliers or hemostats. Just be careful the pieces do not get away from you too much and get out of reach in case you do have to pull them out. You can also add a layer of tubing slightly thicker than the wall of the top tube. Cut it the same size ans shape of the pval hole then glue it to the to surface of the split tube. It will act as a locating piece that will keep the tubing from sliding around in the TT once you install it insode the tube
Just another idea you might try out.
Chombi
Last edited by Chombi; 03-05-12 at 08:18 PM.