Juicy 5s are pretty much ancient and the amount of time and money to service both the master cylinder and the pistons, both of which likely need it at this point, would be better spent towards basically any new brake--the usual suspects being entry level Shimano brakes for less than $50 a pop.
I basically refuse to bleed these if they're not already in more or less functional condition (ie, if they just feel slightly spongey), and warn customers if they don't work well after a bleed they're still responsible for paying for our labor.