Where can you find a key for your slot machine?

I have recently acquired one of these machines from a client who owed me money and couldn't afford to pay his invoices, so he gave me this machine instead. He also had a huge bag of tokens. He did not have the key however, and the reset button is apparently on the inside of the machine. How would I go about getting another key for this machine?

Michael

951-544-0140 Cell/Text