About 20 years ago we switched from a gear tower system with 3 or 4 gears mounted in a brass box, to a belt drive. Since then we have had almost no failures. If there is something else in the model binding, or a pulley pin works loose, the friction from these things rubbing and trying to transfer torque from the motor can melt the pulley or tear belt. Luckily these belts and pulleys are the same going back 20 years and 10s of 1000s of steam engines and very easy to replace. Really, we only get maybe 1 request every couple of years for replacements. They are much better than the gear towers of the past.
Unfortunately, the builder for the Selkirk who is long gone, used Loctite on the flywheel and motor shaft. One needs to heat it up to get it to release. I suggest a hair dryer. I was so angry when I saw them doing that, but it was too late, all the chassis were finished. They gone now and we have much better control of production than we did back then. I really should write a book on importing these things.
If you need belts and pulleys, email me. We sell them.
Scott Mann
