Originally Posted by Prowler

AFAIK soldering iron tips are copper or a copper alloy. May be way too soft for excavations. It's great having a variety of dental pick. Quite useful for this job. And I don't think a hair dryer would be hot enough but hot air guns are not expensive and, like Grandma's lye soap, good for everything in the place.

OP, As to drilling out the cable head: keep in mind that the cable end may look like a round lead button but remember that end is mounded over the end of the cable. The wires inside may even have been flailed out a bit prior to getting potted. I've drilled one out but it's very difficult as you quickly engage those cable wires which aggravate the drill point and ruin the nice hole you made. I don't know a good way but take care. Maybe a carbide cutter in a dremel type tool. I don't think my hand is steady enough for that.