Pretty sure the Greyhound Electronics games don't have free play option (or any dipswitch coinage options). This is based on having worked on a GE Joker Poker (same hardware, different ROMs), and looking at the MAME driver:
http://mamedev.org/source/src/mame/drivers/gei.c.html
Check your coin switch, wiring, connectors, & edge connector. If everything checks out, perhaps consider swapping out the 8255 (the one connected to the coin input line). Oh, and look over the PCB for mods; the Joker Poker I worked on had some wacky mod on the credit line.