I didn't use them because I didn't understand why I needed to.
The ceramic capacitors are more than likely used to quiet down the interference from the motor. Read up on a decoupling capacitor for more information. As PeterH had said, have you tried putting them back into the circuit?
A decoupling capacitor is a capacitor used to decouple one part of an electrical network (circuit) from another. Noise caused by other circuit elements is shunted through the capacitor, reducing the effect they have on the rest of the circuit.