Did it rotate to make a wah, wah sound?
It did not make the "wah, wah" sound you hear when the player alternately mutes and un-mutes a brass instrument such as a trumpet. The Leslie sound is quite unique, but can probably be reproduced today fairly easily with a Digital Signal Processing (DSP) chip.
The Leslie system was an "add on" to an existing electronic organ. It generally had two loudspeakers with a 800 Hz cross-over frequency. The low-end range audio loudspeaker (woofer) did not rotate. Instead it faced (usually downward) a baffle that rotated at a variable rate of speed from slower (chorale effect) to faster (tremolo effect),
Read the Wikipedia article and play the "sound bite" near the beginning of the article to hear what the Leslie effect sounds like. It is unique among musical instruments in that it both amplitude modulates and frequency modulates (through the Doppler effect) the sound emitted from the speakers. There is a low audio range speaker (woofer) that is usually pointed downward toward a rotating. variable-speed, motor-driven baffle. There is also usually a high audio range horn-speaker (tweeter) that also rotates, but I have no details on how that was implemented.
In the Conn electronic theaterette organ that I once owned, the Leslie low-end woofer speaker was mounted horizontal (probably to save space) in front of the rotating baffle. The effect was not as pronounced as the one heard on the Wikipedia sound bite. There was no Leslie high-end tweeter in my organ.
Electronic organs are a lot of fun to "play" with, both musically as well as electronically, but I must have a "tin ear" because (1) I never learned to read or play from sheet music, and (2) was never, ever, asked to play the organ.