If the owner of the pub does not own the machine, they should contact the machine owner who will send out an engineer to investigate. It might take a couple of days, though.
As indicated in the other posts here, fruit machines in pubs should have a disclaimer on them stating if the pub are not responsible for the machines or losses incurred. If there is such a sign on the machine it should have a phone number to contact the owner of the machine. If there isn't a sign on the machine the pub could be responsible to refund you.