How can I fix my fruit machine, barcrest rainbow riches, model Horizon?

Ok so what happened was I pressed collect and there was insufficient coins in the machine to pay it all out now an alarm sounds saying attention call manager! How do I put money in the hopper so I can stop the alarm and play it again? Many thanks. More info, game version, base kit UK dual hopper horizon plus. Serial number, 964173020. Category type, c/ complex D. Date of manufacture sep 2009, murphys millions. £70 jackpot