After some difficulty in measuring the corresponding screw on my GV1, the threads appeared to be 1-64. The shoulder measured .110 inches diameter and about .050 long. Even if you can find a 1-64 screw, improvising that shoulder might be difficult. However, a long screw might work well enough without a shoulder if you check it occasionally to see if it is screwed in about the right amount. Better yet, try winding the right diameter and length of wire into the grooves of the screw.