Wonderful article on the 13D! It is so interesting to hear the words from the man himself (Oscar was a CanAm driver and founder of the Auto World Catalog). I dealt with Mr. Erwin Polk myself briefly a few years later in my manufacturing business and he was still the only dealer of Mabuchi motors in the US at the time.
The big news for slot car motors from Mabuchi may have been the 26D as opposed to the upgrades leading to the FT-16D model. PdL has a great Slotblog thread on 'Understanding the 16D'.
I personally loved the 26D although it became the swan song for Mabuchi and slot racing. I had great fun and some success running them. They really lit up the imaginative 'Thingies' and feather-light race cars of the time. IHO (not based on much) the fabulous 26D motor was hoped to offset all the American companies hopping up Mabuchi's 16s. The aftermarket companies were pushing Mabuchi beyond what they could achieve and still remain in the economical mass production toy motor business. When the design flaws of their whistling ball-bearing monsters ignited the 26Ds into flaming smoke bombs it probably had a catastrophic effect on their bottom line if not their enthusiasm for the slot car market. The horsepower wars were in full swing and Mabuchi (pretty much) pulled out.