If you have to go with an angle grinder get some good cut off wheels. Cut the shaft as close to the crank pulley as you can. Then cut it into a pizza. It goes in pretty deep and you'll have to cut into the 3L crank pulley a little bit but it doesn't really matter since it's getting tossed anyway. Once you've clearly cut deep enough you can use a hammer and whack the pieces together to relieve pressure and then spin it loose with a few taps from a screw driver. I'd say every 10th motor we get has to be done this way. It really sucks.