[Volt_Ampere]

Easy to work on - no electronics to let the magic smoke out of. :-) You might have a stuck solenoid. Sounds like as soon as the main solenoid closes, you have full power. You should have all of the resistors in series with the motor when the pedal is just pressed. The further you press, the more solenoids are energized which shorts out some of the resistor coils. This is how it increases the power delivered to the motor.