You insert your paper CharlieTicket into the gate, and the gate refuses to open, saying “NOT ENOUGH VALUE”. Do you throw away the ticket and buy a new one? Lots of people do, but if you’re one of them, you’re throwing money away.
Instead of buying a new ticket, put the ticket you already have into the Fare Vending Machine. The machine will display the ticket’s current value. Let’s say, for this example, it’s $1.25. Now select “Add Value”, then “Other Amount”. Enter the EXACT amount that you need to add to reach $2.00 — in this case, you would enter 75 cents.
Now insert the needed amount of cash. Don’t worry about having exact change, as the machine will give you change if necessary. Once you’re put in the money, the machine will spit out a new $2 CharlieTicket. Go back to the fare gate, use the ticket, and throw it away. Then don’t buy any more tickets — get a CharlieCard from the station agent, and fill it with cash for all future use.