No, close enough I reckon.
Had another thought, and this one is even better than the last one re ROM setting. Check the jumper section; if the machine is jumpered for overseas that may preclude the credit knocker from working. To set it up for US (standard) you need to ensure that W14 through W18 all have jumpers in place.
They are located on the CPU board, just below and slightly to the left of U9 (a large mostly square IC). The jumpers themselves are designated as 0 ohms resistors, that is, a link. If you have no spare jumpers available you may be able to get a way with a bent paper clip (any comments on whether this is OK?).
