@GroundFungus how do you determine the value of the capacitor C1 ? on your picture, you put 0.1uF, I have 100uF does it work also?
A lower value would work better. That cap is there to shunt away the high frequency noise from motor brushes. 100uF won't really do much for the noise. 1uF would be better.
0.1uF caps are used so much that I buy them 100 at a time. They are one on those parts that should always be in stock.