Hello just found my third slot machine in 3 years. This one is a Mizuho Marine Battle having issue with it is not showing credits when putting in tokens. I have tried resetting multiple times, getting the flashing light (bomb) stating insert medal. I tried quarters by passed and spits them out, thought possible issue with coin mech cleaned and tested shows lights blinking on board? Just kinda stuck on what next to try. I only have about ten tokens so order some from eBay yesterday, thinking it may not play till has a decent quantity in hopper for payouts.

Any help would be greatly appreciated