In the following video

I think I have evidence that a spherical weight can roll upwards under certain very specialized conditions:

https://www.youtube.com/watch?v=g9Zpdjj1bWs

I measured from the floor on the right and left edges of the marble's movement, and it appears that the right side was higher than the left. Mixed results with a level, although clearly when measured on a partial contingency, the slope is upwards.

My explanation for the theory is that the forwards angularity of the marble is steeper than the difference between the horizontal slope and the vertical slope, corresponding to the two pieces of cardboard underneath the marble. A very special case, if true.