Hi Im assuming you are talkng about a necta colibri vending machineAnd that when you say that it fills a 1/4 cup you are receiving milk powder and perhaps chocolate powder but not sufficient water.
if this is the case
1.check the mixing bowl for blockages remove and clean
2.check the tubes for blockages remove and clean '
3.unwind the whipper blade by blocking the cog with your finger and rotating anti clockwise the small disc (revealed when you dettach the mixing bowl housing )and clean behind
4.flush the system pushing button on inisde of door closeset to hinge
.check water volume if this is low or very little after you have performed the above cleaning . you may have a stuck valve
or a pump problem or a faulty volumteric(water flow counter)
5.check the grind has not been set to fine and rotate the control knob(located below bean hopper towards to the big dots to coarsen the grind this will allow greater water flow ( also reduces strength of coffee)
Cant help you with suppliers in CA as im in New Zealand hope the tips help
good wishes Steve