How would i repair a Gilera H@K Speedometer drive?

Hey there, well basically i have a Gilera H@K 50cc road bike and i have discovered that the speedometer does not work. I unscrewed the cable and with my fingers, twisted the cable as the bike would generally do while its moving. As i did this the speedo moved and was showing that the cable was not damaged. I then took the front wheel off the bike and removed the speedo drive. I removed the full cable so i could do some tests and i found that when i put the cable in the actual squared out hole that it just spun freely. the square shape has been worn down on the actual worm gear not the cable its self. so i was just wondering what would be the best way to get that square shape back, i was thinking about either taking off about 0.5cm of the hole then adding a home made piece that had a square hole cut out of the center. Would this be a good idea? or is there something else i could do like fill the hole and push the square rod through? I cannot find one of these on the internet well the only one i can find is over £40. I don't really want to buy this as i could easily just buy a digital speedometer and fit that to the bike. Thankyou in advance :D

Go down to the local aero or railroad modelling store, and take the cable. Get a piece of K+L square brass tube, that fits nicely over your cable end, and glue it into the back of the speedo.
god ownz (author) 5 years ago
I ended up simply taking a strand of copper from a piece of wire and spun it onto the square cable which basically formed the square shape but thickened it with the copper, similar to Steveastrouk's idea but i did it before i actually seen his post (sorry) :) thanks guys.
Your on the right track. Widen the hole a bit and use a good epoxy to fill the hole and insert the cable into. If it doesn't work out then replace it.