Where are they currently stored?
Are they clean or do they have candy / dirt build up from sitting?
Are the machines complete with all parts and keys?
Have 2 Keys but more are in a box in the garage somewhere along with some screws for the base. Currently going through the boxes to locate them. Will update as soon as I have my hands on them. I also have some spare trays and heads (holds the candy,etc.) and a large container to hold the extra heads (holds 6).
Are all of these machines only capable of 25 cent purchases (can they be adjusted to accept 50 cents?)
They are single quarter only . 1 out of 3 heads is a 1" inch gum ball or capsule dispenser meaning there is one for each stand with three heads. It doesn't seem adjustable.
Do they only work with gumballs? Can any heads work with 1 inch toy capsules?
Yes if it is 1" or less. I only used gum balls simply because the profit was better at a quarter a piece.