First remove the metal shield. I used an X-ACTO saw to cut the angle in the plastic. A hacksaw will do nicely for excising the six pins and plastic waste. Then use a file to round the plastic off to DB-19 cross section. Leave the old the shield off, as the plug end shield works fine.

When you're done playing with the FDD project, cut it down to fifteen pins for playing with sense lines/video settings.