Geoff runs OO9 (OO narrow gauge – runs on n gauge track) and asks readers:

“I am trying to fit a decoder to the Tomytec chassis TM-07R.  The chassis works fine on my DC test track, and the decoder is fine on my decoder tester.  But when I put the two together, everything is fine at first, then after a few minutes it slows to half speed, then it randomly starts and stops, and then it goes to full speed, at which point it doesn’t obey commands to slow down, and I have to use the emergency stop button.

I’ve tried with two different chassis, and two different decoders (same brand), same result.  My system is the NCE Powercab with their SB5a booster.  All my other DCC locomotives (that were fitted with decoders at the factory) work fine.”