I first took apart the old wires then cleaned and saved the end parts. Cut some new wire 1" longer than the original wires. Trim the outer casing back 1 7/8" + 1/4" then trim the inner casing back 1/4" leaving bare wire. Slide on a 1 1/2" length of the heat shrink tubing then the plug wire ends in the same order as taken off. The bare wire should come through the hole in the plastic furrell, separate them and bend them over, insert small nail into center of the wire mass, this should lock the group into place. Hold the wire with everything hanging down and heat the shrink tube starting at the bottom and working your way up, this will allow better control over the tolerance at the screw on cap. Some of the adhesive will ooze out at the ends of the heat shrink this is normal leave it there it helps the seal. You can see how much thicker this gets than the stuff on the old cable at top of Pic.
Here is where I got the tubing but it may be available locally. I used Heavy gauge wall Heat shrink tube with interior adhesive. 3/4" 3:1 shrink ratio to 1/4" Available in red and black is usually used for Battery / Jumper Cables.
http://cgi.ebay.com/ebaymotors/3-4in-He ... 0001101068
Hope this helps, Miles