Bally Pro Slot intermitten coin accept with compairtor

[Jackpot]

Who can help solve this one?  I am going crazy with this problem. The machine has a coin comparator and trying to coin this machine up is a nightmare. I have replaced the coin comparator with a known tested good one. I have also pulled and cleaned all the legs of all the EPROM's on the CPU board. It doesn't acknowledge all the coins accepted. It's a 5 coin joker poker machine, and I might have to drop 20 coins in to get 3-4 or 5 if lucky, to requestor. I have also changed the coin in the comparators cradle, still no change. I have wiggled every plug on the mother board and comparator in case there was a weak connection. While feeding, it coins trying to get it to coin up, every once in a while I get the reverse coin in error. The only thing I can do to that seams to make a little différance is to shoot the cons in at different angles or slam them in, seams like it will accept them a little more often that way. I have gone into an input test which shows all 1's, and inserting coins will toggle Callum 3 every once in a while, but not constant. Has anyone been through this hell before?Thank You for any guidance you may shed on this.Jackpot     

[Amechanic]

Have you checked the black plastic coin guide, that guides the coin past the optics? They come in 4 difference sizes.. If yours is too large, say a $1.00 guide trying to play nickels, the nickels may never past through the optic beam, or register a credit..