Perhaps an option to drilling and retapping: use a Dremel tool with a thin reinforced cutoff wheel to cut a flat slot into the remaining portion of the broken bolt. Turn out the broken piece with a screwdriver.
Funny washer repair story: a buddy of mine called about his machine, as it was screeching making stink and not turning the tub. We both agreed it was probably a belt(s) so I picked up replacements at the appliance store and stopped at his condo. (Background note: he's been married for a few years and his wife is an ultra shy person). New belts installed, and the belts start to screech immediately in spin-still no tub motion. My buddy is worrying about the cost of this whole deal to his wife, and then I see it. A piece of cloth is stuck in between the inner and outer tubs. I grab it with a pliers and move the inner tub back and forth until it's free. Turns out to be a lacy pair of ladies panties which now look like they were attacked by a rabid badger. I walk into the living room, hold them up and remark, "It's nice to see there's still passion in your relationship." She turns redder than the undies, and he's laughing his ass off.
