N Cook wrote:

snip

But just wondered if anyone has tried heating a revolving 1mm pitch brass
cog and remelting a nylon cog or any other technique ?

Not exactly a solution to the problem you described, but here is my page
on (re)melting a nylon gear as part of a repair to a lift-chair screw drive:

http://www.cybertheque.org/homebrew/gear

Michael