i bought the same machine a few months ago. my black lead that connects to the graphite block ends in a plug that plugs into the block, and was made to be removable. do you have an older model that was permanently connected to the block ? if you can re connect that wire it will still work as good as new. my plug has a small silver set screw on the side of it. if you have the same plug, remove that screw, get the corroded old copper out of there with a toothpick. soak it in some windex or whatever you use on your stamp to neutralize it. cut your black wire off an inch to get rid of the corroded copper, strip the wire, insert it in the plug and put the screw back in.
