1960: The Making of the President, support cubes

I feel I’m being very foolish but I just can’t figure this out.
By what method should I be re-seeding the support check bag with twelve cubes of each colour if it runs dry mid-round and how am I to move the cubes on media support to the bag on election day when the only function on those spaces is to increase support for one side or the other?

Any assistance would be greatly appreciated.

In both instances the solution is to open the piece palette (the button in the toolbar called “Cubes”) and drag cubes of the needed color one by one onto the “draw pile” in the Support Check window (the image that looks like stacked cubes with the white question mark on it).