CAVE released 3 program revisions of Ketsui. They did not change the version number on the EPROM label nor did they change the date on the region warning screen. The only way of determining which version you have is by counting the number of periods in the version string.

The following bugs have been identified in revision 1 of the main program:

BUG1: Demonstration crash, after toggling SW1.
BUG2: Freeplay crash, if you press the start button in demonstration mode.
BUG3: Music at half speed on stage 5 after button mashing between stages.
BUG4: 1'st boss, chip counter discrepancy.
BUG5: Freeze bug, game freezes due to button mashing between stages.

How to use this ROM image with your PCB:

Your Ketsui PCB has one 27C160 EPROM at position U38. Take the ROM file from the zip archive you downloaded from here and burn it to an EPROM of the same type using an EPROM programmer. It should work by reburning the old EPROM too, if it is erased properly first.

Hint: A useful method to remove an eprom from a socket would be to stick a flat screwdriver between eprom and socket and then to rotate it carefully until it lifts both sides of pins out of their slots. Always keep an eye on the correct direction whenever you place a eprom into a socket (Look out for that small gap at one side of the chip. Find the same gap imprinted on the surface of the PCB)