[Richard Crowley]

"EADGBE" wrote...
I should point something out that I haven't mentioned before...
There are two slots in the circuit board.

One of them is just above the smaller black electrolytic capacitor,
and the other slot is just below the larger blue electrolytic
capacitor.

You can see the traces going to these slots and appearing to "stop
dead".

These slots are where the motor contacts are soldered.

Then it appears that you didn't trace the circuit properly.

According to your green lines, the only path from the
upper motor node is through the adjustable resistor
at the top (highly unlikely for such a high impedance
as 5000 ohms) or through the black electrolytic
capacitor (electrically impossible).

How about just posting a photo of the BACK of the
board instead of trying to interpret it?

There IS a direct path from the +power input to the
lower motor node, which seems consistent with the
motor speed regulator IC circuit.

Did you say that you *have* a replacement for the
semiconductor in hand, or that you had simply
identified it?