Older HVAC blower motor spd control puzllers

Hi All,
This is for old-timers, or those who know everything. Have an old Lennox
furnace-A/C, about 2 tons.
Got into it to clean the blower fan, which is squirrel cage design and have
discovered a couple things I do not understand.
The motor is made by GE, but does not have a nameplate. It has one two
wires for power and one wire (quick connect) going to a small TB, right on
the motor. Changing the position of this what seems like speed select, does
not seem to change the RPM, at least by listening. FL current changes a
bit - this is with motor not coupled to the fan. Motor seems to be 6-pole.
Asked my friend in HVAC business, but he could not explain, except that it
was for speed control.
Puzzler 1: What kind of motors were used for this application and what does
the extra wire do - add winding, some internal components that I do not see?
Puzzler 2.
The fan housing has a small connection box on it. In it is a 3-wire device,
which is only labeled as Basler Electric BE-8565, for SP Motor. Black to
Yellow 5.3A, Black to Red 4.8A. It does not appear to be a capacitor. In
this case it was connected to yellow, but the motor runs w/o the device,
even faster.
What am I seeing here?
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