All of the motor boards I have seen were machined to accomodate either a single or double spring. The winder/spring retainer on the singe spring is longer and uses four screws to hold it to the motor board, two on each side, the shorter one for the double spring uses 2 screws, one on each side. In the past I have made a single spring motor into a double with no problem. If this is not clear let me know and I will see if I have drawings. I believe the long play kit came with a second spring.
Steve I believe all DD motors were able to have a second spring barrel installed without >modification...and that the barrel was available separately for the >purpose of the conversion.
