Something else I've seen posted to help this situation is putting blobs of solder on the contact pads. Either the decoder PC board got thinner or the chassis slot for the board got thicker, either way the result is less solid contact than before and a little tweaking is required.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
As Lee pointed out, sounds like a motor contact problem. I shaped the two brass motor contacts so that the ends that go under the gray clip were curved upward at the clip. Once that clip is installed, the extra spring pressure keeps them in contact with the decoder pads.
Martin Myers
Sounds like a motor contact problem. Double check the motor brushes and make sure they're making solid contact with the tabs on the decoder. If all else fails, send it back to Digitrax with a copy of the receipt, and they'll send you a replacement. You can find their warranty form online at their website.
Lee
Route of the Alpha Jets www.wmrywesternlines.net