In my theory the planets would have to be aligned just prior to the sunspot cessation and all pulling on the Sun in the same direction for this to happen.
On August 3rd, 1642 this is how the planets were aligned;
August 3, 1642
Imagine the yellow circle is a loose fitting bottle cap and the line is your hand moving forward and rotating the bottle cap. That is exactly what the planets did to the Sun in 1642. It was a shearing force that accelerated the Sun’s rotation on its axis. The force is multiplied when the planets align like this.
Within days/months sunspot activity had ceased on the Sun in 1642 and Earth entered a cooling period. The period is known as the Maunder Minimum, but better known as the “little ice age”.
On September 8th, 2040 the planets will align again in a similar fashion and Earth will once again begin a cooling cycle.
September 8, 2040
In this depiction it is the same bottle cap only you are pulling your hand towards the cap and it spins off. In the solar world since the sun is just spinning free, the energy is imparted to its rotational speed.
How does this stop sunspots? The additional speed makes the sun spin 3-4% faster on its axis. This little bit of energy is all that is needed to stabilize the relationship between the Sun’s inner core and outer shell. When it stabilizes no more sunspots. No sunspots and the Earth cools.
Now the little burst of rotational energy does not last long and the Sun's rotationa slows down again, and Earth starts a new warming cycle.
This cycle repeats over and over, and depending on how the planets line up different levels of rotational energy are imparted to the Sun making some cooling periods a bit longer than others but there are long term patterns of warming and cooling based on planetary motion and alignment.
If nothing else; come 2040 we may be happy to have a marginal greenhouse effect in place to help mitigate the next little ice age.