How do you change crankshaft seal in a Lincoln sa 200 welder?

To change the crankshaft seal in a Lincoln SA 200 welder, start by disconnecting the battery and removing the engine cover for access. Drain the oil and remove the flywheel by taking off the retaining nut and using a puller if necessary. Carefully pry out the old crankshaft seal and install the new seal, ensuring it sits evenly. Reassemble the components, refill the oil, and reconnect the battery before testing the welder.