You've not said what the actual fault with your timer is, it may indeed need rewiring but a well know fault is the clockwork mechanism getting stuck after the internal lubrication dries out after many years.
IF this is the problem, a really good post was made on this site a good few years ago that gave a comprehensive guide to repairing the mechanism.
Here is the link:
Click on this and scroll down to the 12th reply made by Martin in October 2012.
If this isn't relevant to the fault with your timer, reply with a description of what went wrong and I'll see if I can help with that instead.