bill validator comm failure

[ALIDMAN]

Hi everyone , I got this machine in working condition but it had only 12 games on it , I tried to use my chip 40 to open more games , and next thing I know is I get error massage ; bill validator comm failure and options verification required , I have use chip before and I know it works , I know the machine is working fine and it is me not putting right setting , not sure if it is setting in comm channel set up or some other thing that I am not doing it right , the bill validator is MEI and I do get flashing green light  , I would be thankful for any help.

[rickhunter]

The interface board on the MEI's are really finicky and is usually the point of failure.  I would remove the head, pull out the interface board and clean contacts and look for anything burned or damaged.  If it doesn't look damaged, use a pencil eraser to clean the card edge contacts of any oxidation or tar.