EZ out, Screw Extractor, Left hand drill sound like a good ideas. Only thing you purchase them in sets. Break them you mite as well purchase new pinion. I never found one that small. Brain storming! Drill grub (allen) through, smaller then 3mm, Use 2mm Allan and JB Welled into Grub screw to allan. 12- 14 hours later when dried. Use a heat gun to heat up pinion. gently unscrew allan. Good Luck!! JB Welding the allan key, Dremel off the allan screw, allan is good as new. We live and learn!! I learn not to to use loctite om my pinions.