New ribbon cables would probably sell well. The originals rip at the ends. Def only make them 1x16. 100% of the time the last two pins do not need connected and may cause problems when it is. When the IRQ pin goes the 6840 square wave making chip, it will sometimes lock up the MPU. You can either bend the IRQ pin out of the socket on the 6840 sound board chip or leave it off the connector.

My Big Game came with a 1x16 and a 1x18 FWIW. Meteor had two 1x16. Who knows if that is what they came with form the factory/

You can also build your own connectors for these. Its not hard, just time consuming. Normal 0.100" molex crimp and housing fits.

Every SB300 I fix the i pull out the IRQ pin out of the socket on the 6840. It is happy just floating in the breeze. That just avoids potential issues.

Appears to be a timing issue of some sort. Swapping boards around it seems it is not necessarily the 6840, but the combination of a the MPU, the 6840 and the sound board.

It is best to use 32 pin cables and not hook up the IRQ. I have come across many SB300 boards (the 6840) where having the IRQ connected across MPU j5 to SB300 actually locks up the CPU. Never went down the rabbit hole as to why, but it is common fault on maybe 1/10 boards. Pretty sure Stern realized this could be a problem too as many SB300 games I have come across had 32 pin cables in it. I did not route the IRQ track on either the replacement SB300 or MPU at J5.

You can buy just the cables. Check the pull down options.