MOST OF US who have come to know and love the subway system cringe just a little when it doesn't work as well as it should. But Metro board member Francis B. Francois - one of the subway's dearest friends - has lodged a legitimate criticism. Mr. Francois says the Farecard vendor machines and the automatic entrance and exit gates that collect fares are unreliable and balky and are cuasing losses of riders as well as revenues. "The printers in the machines are not working. People are confused and mad and fee they are cheated," he says. He is right. He suggests the machines be turned off until they're functioning properly - a matter that the board is scheduled to consider on Thursday.

True, tens of thousands of passengers have error-free travel records and are now subway veterans who can spot an ailing vending machine from 10 paces. And true, all those confused tourists are only in town for a short spell. Yet in recent weeks, an average of 10 percent of the 273 entrance-exist gates and about 15 percent of the vending machines have been out of working order when the subway opened for business. And as you may note from the bureaucratic language reprinted For the Record on this page, during rush hours teams of station attendants have been scrambling to keep things moving.

At least the suppliers of the Farecard equipment - which cost $52 million - swear they will do "whatever it takes to make that equipment work." But in the meantime, since it takes humans in all the stations to babysit the machinery in any case, why not use these people to sell and collect during busy times at heavily used stations - to complement the machine service - while the whole Farecard system undergoes corrective surgery?