Yes they can, and were, back in the day we had one with a bent crank and taking the chance that it was maleable cast we had an approx 9 inch long bar turned so that an internal taper locked to the crank with an ht allen screw then carefull "whacked" the end with large hammer whilst clocking the bar on a turned portion concentric to the taper.
We got it to within 1 thou of concentric and the engine ran fine for as long as we had records of it(years)