Hard Grease EZ repair

Try this at your own risk!  I don't even put plastic shells, trucks, etc., in hot water or direct sunlight, because they can easily warp.  I would say a hair dryer at close range might even get hot enough to heat a solder joint to the point of loosening the wires.

Maybe your friend was careful or just got lucky.  But a drop of oil or new grease might help loosen the old, that's what I would recommend.  My $.02.

YIKES!

I think he was just warming up the bottom of the trucks.  What ever he did it worked for him and he was a happy camper.

Interesting solution.  Best way to lubricate tracks for me is to loosen the trucks from the chassis, clean the old grease out with alcohol and a cotton swab and install dome fresh grease.

I wouldn't recommend the hair dryer method either. Too risky! I don't have any K-Line locos, but I buy a lot of Lionel postwar and have acquired several locomotives with the armatures completely frozen in the the motor housing. Under this condition I remove the motor, take off the brush plate, and work some penetrating oil onto the shaft at both ends and after a while very CAREFULLY try to rotate the armature with my fingers only. It takes a while but eventually I can get it out for cleaning. I then clean everything with a solvent including the gearbox and truck assembly, use compressed air to blow out any residue, apply fresh lubricant and reassemble. I also change brushes if needed. After this process, the motors/locomotives run as good as they did when they left the factory back in the 1950's.

Ken