You probably need the exact replacement part, without looking at a schematic. I wouldn't replace a 30K with a 10K, not without knowing exactly what the math is on the rest of the circuit. I might try a 50K Ohm variable in there, though, if the pot isn't a voltage divider, too.
Lots of speed controllers are PWM controllers with a VCO controlling pulse width/duration. Once again, the schematic is the final word. Read the source, Luke. ;)
/johnny
Thanks for saturation of confusement.
So, I guess hot wiring it is completely off the table, huh? :o)