This is an idea I first read of in the late 70's or early 80's, but have not heard it mentioned at least within the last decade.

I have done this for gearboxes with metal gears.  If you examine the gears before and after, you can see where the wear points are, based on where polishing take place, and sometimes that has caused me to install thrust washers, or tweek a bearing point a bit, to adjust.  It's the "shade-tree-mechanic" adjustment, with no precision analysis.

I have not thought it desired to use the same method for plastic or nylon gears.  Just thoroughly cleaning, and then lubricating using LaBelle 108 oil or, now, synthetic ATF, was all that I needed for improved performance, and quieter, smoother running.

I think you read about that here, on the NMRA website. I don't know where to get pearl drops, but I betcha any similar paste material would provide similar results (not to mention, you locos would smell really, really nice!)

It was not a Coast Guard practice, but in 1966 I was stationed aboard a ship with another engineman (our specialty at the time, now called a machinery technician).  He was a fellow car enthusiast and drag racer.  I was in the machine shop rebuilding a bunch of Detroit Diesel cylinder heads, and he was came by as I was lapping the valves in.  He told me that the finest abrasive known was tooth paste.  He used tooth paste as the final step in lapping in the valves on his race engines.  The point being, that you don't need Pearl Drops.  Any tooth paste will do. 

My procedure for break in of Athearn Blue Box engine was always to take off the shell and put a little tooth paste into the gear boxes or on the worm.  I would then run the locomotive forwards, stop, and reverse.  I would continue this for about 15-20 minutes.  Generally the mechanism would smooth out appreciably after a few minutes of operating.  I would then dissassemble the gear box and clean the gears, worm, and inside of the gear box completely.  At that time I would get rid of Athearn's "camp fire in the cab" lighting assembly, as well as the steel clip used to supply power to the top brush of the motor.  I would solder a flexible wire to the brass clips on the top and bottom of the motor.  The wire from the top one would have a female spade connector fastened to the other end and clipped on to the top of the trucks.  The wire from the bottom one would be soldered to the metal on the opposite side of the trucks.  Finally, I would put everything back together with the shell off, apply full power to the test track while holding the locomotive in place with a finger, and using a pencil with a good eraser in my other hand, Iwould clean the commutator with eraser.  The final step was to use my smallest precision screwdriver to clean out the segments between the commutator bars. 

Just for "kicks," one time I hooked up a multimeter between the power pack and the track and checked amp draw before and after.  The brand new out of the box Athearn, with the light removed, drew 1.5 amps out of the box.  After the tune up, the same locomotive drew 3/4 of an amp.

Joe talks about it here.  Hopefully he'll chime in with an update soon.

http://siskiyou-railfan.net/e107_plugins/forum/forum_viewtopic.php?847.0#post_855

Pearl Drops is available on Amazon.com

http://www.amazon.com/Pearl-Drops-Whitening-Flouride-Anticavity/dp/B001E725SS

Steve

Thanks to all of you for your responses. I thought pearl drops might have had some kind of mild abrasive in it that would polish the gears. If any toothpaste will do thats great. I did'nt know if anything else would give similar results like a polishing compound or as mentioned a valve lapping compound. I have installed DCC decoders in some of my locos and have'nt had any problems with them but any effort to lower amp draw and improve performance is a plus and I appreciate your thoughts. thanks To MRH for a great forum site.

Mark