If you're running on regular DC, most of the problem comes from too high a starting voltage being issued from the pack to these essentially micro-sized motors. You can control that by putting BIG (like rollaids-sized) big resistors of 10W or 25W across the terminals, that will do the trick. I put 35W across my old HO throttlepack to get control where I wanted it. https://www.westfloridacomponents.com/R036/25W+5+ohm+10%+Wirewound+Power+Sandblock+Resistor.html On my Hickory Valley portable layouts (straight pure DC), I have an additional old MRC rheostat set on the input right on the module itself to 'dial up' the resistance so I get the control range I want. These are typically in series rather than across the terminals. I picked up a Golden Dual Throttlepack at a yard sale just to get another couple of those for $10. I tend not to use pulse at all to run these; I have a transistor throttle on the large ATSF layout but I dial down the input voltage (with a rheostat) so that it still works but the pulses are much milder; the locomotives run much cooler and quieter. If you're running DC into a DCC chip locomotive on dual mode, the performance usually sucks, and WARNING WARNING WARNING... many of the dual-mode decoders cannot handle pulse power input in dual mode, only straight DC. I blew a Bachmann decoder doing that. Stay on straight DC if you're running dual mode. If you have a programming track for DCC that you can tinker with the CV's, there's usually one for the minimum starting voltage on DC that's issued to the motor in dual mode. Somewhere. I did a bunch of TCS decoder installs on my Climax kits, and the last ones with dual-mode decoders had such horrible performance.... well, that's why I'm still in pure DC or DC with transistor throttles on my little guys. I thought it was just my own ineptitude, but tech support at TCS couldn't help, and neither could my DCC master friend Lee Weldon. The real problem that I've had with dual-mode decoders is that when there is a stall, they have to go through a sensing routine to determine where the power is coming from, prolonging the stall into the hesitation range. The smaller and lighter the locomotive, the worse the problem gets. The older TCS chips that didn't have dual-mode sensing didn't have this problem.