Okay, checked the other two, which are sd60m's, and they were soldered to the trucks. I don't know if the sd45 were supposed to be soldered but now that they are, I've run them for a while and they run great.
I've been thinking about this and here was something that I remembered. On both the genesis and the rtr boards all the wires are twisted, pushed trough the hole and the plastic clip pressed on, on the wire end that goes to the trucks on the genesis they were tinned. Well when you push the plastic clip on the regular wire, the wire spreads out some, on the tinned one it doesn't,maybe it wasn't making good contact. I've got two other genesis that have not give me any problems that I'm going to look at after typing this.
I'm wondering what the connections are between unsoldered connections and slow speed performance.
Alright, I got it fixed! I got my hands on a dc board, slow speed in dc was good, plugged a nce decoder in, worked good but noticed it was acting finicky. Looked everything over and I had not soldered the wires on the trucks. On everything else I have put a decoder in, I have soldered every connection. I put the sound decoder back in and soldered every connection and it works great! I can believe I overlooked something that simple. Hopefully somebody can learn from my mistake.
I'm using nce power cab,I have messed with the starting voltage and all that did was when I got to step 8, it would run faster. I put a new tsunami decoder in it , roughly same thing. I 'm running with the shell off and it seems like the motor is electrically locked up until it breaks free at step 8.
Which DCC system are you using? Read the instructions on how to program a CV, and increase the value of CV 2, Start Voltage, in the decoder.
The locomotives should have come with documentation containing a CV listing for the MRC decoders, and indicating the factory set value for CV 2. Increase it in incremental values of 2 until the loco begins to creep on speed step 1. Try to switch to 128 speed steps, instead of 28.
Unfortunately, you may be out of luck. The documentation I have for an MRC Sounder does not list CV 2 as one supported by MRC. Another reason I'll never again use one of their decoders.
OTOH, the Athearn Genesis MRC decoders may be ones that do support CV 2. If so, the factory default is set to 0, and the acceptable range is 0-32.
A much more elegant but expensive solution would be to replace the MRC decoder with something better such as LokSound or Tsunami. Some MRC decoders are known to have issues with slow speed control.
I've got 2 genesis sd45-2 with mrc/sound that won't move until step 8 on a 28 step. Once they get moving, you can slow down 2 steps but anymore and they just stop. I've checked for driveline bind, changed decoder on one, changed the motor, messed with the motor programming. What am I missing here?