Good luck. Those juicers are a b* to clean. I'm not sure if a food processor would work, you'd have to strain it I guess? For what it's worth, one whole bunch of celery only yielded a half cup juice for me.
I call it a food processor, might have other names I suppose. It spins juice out one side, another shoot directs into a fiber basket. I used to make gallons of cider with this.
From what I've seen, the "food pros" ect on you-tube and health websites such usually use these monstrosities, vs the blender or smoothie types. I'll get something else eventually, that's smaller and easier to clean.