Well, thank you for the compliment, Deve.
I'm not entirely sure what you found. But for any others who are interested, check out eBay (or even Aliexpress) & apply search parameter "DC 9V 12V 24V 48V 60V 20A Motor Speed Controller Regulator Driver PWM 25KHz"
It should give you several units to choose from.
Be sure to get something where the circuit is enclosed in a box as it will act as protection, and as a heat sink in the event of higher draws.
This is a whole different ball game from what was discussed earlier on the topic -- the pot on this PWM device generates no heat at all in any of the speeds. The tiny pot only adjusts the bias of the internal ss devices. I would assume one can replace it with a physically larger pot but with same 100k value. This might make it easier to manipulate at the dash.
..I'm confident your bench test will also prove this out as a nifty solution.
As suggested previously, coupling this device with a 12~6v step-down buck converter on a 6 volt motor could also be an interesting experiment. It may save having to find a 12 volt motor replacement. But I'll leave that for someone else to post here
