I posted a message on this topic previously but received no replies. I have exchanged two On30 shays because of poor running and just received the third. The third shay exhibits the same problem as the first two. All three shays bind at slow speeds and as the speed increases they begin to run but wobble badly and make a loud clunking noise. Has anyone had this problem? Do the shays require some adjustment of the drive mechanism before running?

I recently purchased a Bachmann On30 shay and exchanged it for another because it would bind and stop at slow speed and wobble and make a loud clunking sound at higher speeds. I just received the replacement shay and it does the exact same thing. Any thoughts as to the cause of this problem?