How do you know the attract mode is on if it is not working? Do you mean attract sounds are not on? Attract mode is just a series of insert lamps that flash in different light shows to attract attention of a potential player once the game has booted and is ready to be played. The attract sounds can be turned on/off separately.

Attract sounds on most all games are default off if the batteries die or you replace them when the game off or if you install NVRAM. It can be turned back on in the adjustment menu.

The attract mode is only the insert lamps that are always cycling different patterns and are always on as long as the game boots and is not being played. This is to attract people to play the game.

No flashers are on during attract mode to conserve power.

Attract mode sounds are default off if the batteries die, change batteries while game is off, or install NVRAM.

Turning on/off the attract sounds is the only adjustment that is available in the adjustment menu.

What version is the game and sound ROMs? I would press on all the socketed parts on the MPU and sound boards.