If you are putting a new GP in, then why care about whether you brake the threaded GP tip off or not? If you can get the wire off, even with the nut still attached, you can put a vise grip on the thread and wrench the nut off thus saving the wire.

TIP
To ensure that nothing falls into the GP hole, use a shop vacuum to suck up any loose sand etc, that maybe sitting around the GP before you remove it.