Picked up ANOTHER 4-piece boiler 302. This one doesn't run, which is fine with me, and has the wrong tender and shell..While putting power to it, it would run 1/2 revolution and then bind up TIGHT!!. Quartering is off, right?? Well, I pulled the linkage off and the same thing was happening...The next thing you want to check is the smoke gear. I pulled the loco down to it's bare chassis, and the smoke gear was so loose, it was wobbling and causing the armature to bind. One good whack with a brass punch and a small hammer on the smoke gear pin and it was fixed. No more binding.. I noticed another thing with this loco, someone had put on a pair of pul-mor rubber tires on it. The tires are in great shape so I'll pull them off and return it to original.