thinking out loud

with 3 machines i would mke a very verry shallow ramp to all 3 machines.. something like a 1% grade.. then your ball lifter would lift above said ramp allowing balls to fall onto the ramp.. the balls would fall and roll down hill to whate ever direction.. as that machine filled up the balls would be shifted to another machine as needed.. then to the 3rd machine as needed.. then once all machiens were full the balls would start to stack up and fill the ramp where ever there was room.. as a machine needed ball they would fall in that direction as needed..

your problem happens with weight or a machine winning allot.. (mordern machine hitting a feaver) then you jsut flat run out of balls.. now if the ramp were made heavy duty and you had enought balls there is no problem..

it would take some trial and error but the only way i see it working is storeing large qty of balls up top.. most lifters work on the premiss of keeping the bulk of the balls at the bottom and shifting up only when needed..

hope this makes sense