Eccentric Cranks *PIC*

The eccentric crank is swung to the oposite side of the axle. Unless the reach rod’s connection to the reverse crank or Johnson bar has been changed, the engine as it is set up will run in reverse when the Johnson bar is set forward... Oops!
Eccentric cranks are very securely keyed to the crankpin, with a square keyway and a slot milled into the crankpin to lock the eccentric crank in place. Swinging the eccentric crank to the other side of the axle would be quite a job, and the empty keyway and slot would reduce the area that the eccentric crank had to bear on the crankpin.
Replacing the main crankpins would cure the problem, but would require dropping the wheel set, and new crankpins would be required since the old ones need to be destroyed to remove them.
Another solution would be to end-for-end the main driver wheel set, i.e. left to right. This would set the eccentrics to the correct side of the axle, but would be a big job in its own right, since it is likely that the shoes, wedges, and rod bushings would all have to be remachined to proper fits with their new mating parts.
I snagged this photo from [trains.nute.ws] to illustrate the conventional location of the eccentric crank on these engines.
It could be that they set it up this way for a good reason, I'm not there.