Under no circumstance should you..."strip the rubber from the wires, solder the copper, and wrap them in tape." It would be potentially very dangerous even though it would work perfectly well up until the time you electrocuted yourself.
The best method is to open the unit and either fit new cable or just shorten the existing cable - you need to be confident with hand tools to do this and be able to overcome some minor frustrating cable routing and connecting problems.
If you replace the cables then just buy two-core flex of the same diameter - your question of Voltage & Wattage suggests that this is a whole new world for you.
Another, and by far the easier solution is to fit an in-line connector on each end of the damaged cable - male connector on the machine end and female connector on the long cable.
An alternative is to have a handyperson do the work for you - a poor retired chap - couple of pints of beer. I live in Reading UK
Peccavi
June 2009