I found the e-mail I received from Dean in customer service at Lionel a few years back with how he changed the traction tires on the Cab Forward. I followed them and it was easy to change them.
What I do is position the screw between the main rod guide, disconnect the eccentric rod and main rod assemblies and pull the main rod back out of the way, you can access the screw after this is done. Reassemble in reverse order.