this is the 2nd time we have replaced the regulator, 1st time we used the W410 and redid the wiring, soldering as directed and this produced a satisfactory result for nearly 2 years. We tried that again and it did not work, bought a W210 regulator that was suppose to be an original parts replacement. The part that bolts to the fan motor is smaller than the original but otherwise bolts up fine and wiring correct. What other part could be causing the random off/on situation