Not with board disconnected, the sounds are routed through the speech board, mixed with speech and then back to sound board.

Looks like you have a solder splash between pins 4 and 5 of the top socket.

Here:

socket1 (resized).jpg

It has been a few years since I sold my Alien Poker, but as I remember the speech test says:

Alien
Poker
You
Deal
Big
Winner
I
Fold
Million
Jackpot
Joker
Raise
Royal
Flush

Yes, clean the ROM legs, and if that does not help, I think replacing the ROMs is needed, since you already replaced the sockets.

No need to do anything with the actual sound rom, since the sounds work and it tries to do some speech. Problem is with the speech roms or ribbon connector.

You can, but be careful when opening the speech board connector and removing the old cable, so that you will not damage the connector. The speech board side is hard to find, the sound board side is a standard flat cable connector.

Yes. Make sure all the wires are aligned with the pins and you press the top evenly across the connector.

Knowing there is a new board available is a good backup strategy, but nothing beats the feeling you get with successful repair of the old board