Hello, I have a 1980 Black Knight and I'm having trouble diagnosing this new issue. When a drop target falls the timer light and sound have slowed way down from what it normally would count down before resetting the targets. Also, the game is set up for just 3 play balls. The game will not end after 3. It will just keep putting a ball in play when ball passes flipper and should end game. I went up to 10 balls before powering off. This all happened at the same time, so it must be related.
Anyone have any ideas where to look for this problem?
Thanks.

I should have added that I just replaced all boards (except power supply) with new ones from pinballpcb. The games worked great for about a month. I first thought the ROM too, but what could kill a new ROM that quick??

Thanks for the input everyone. I took the game ROM from my old board and put it in the new one as soon as I got home. That did the trick. I guess they had a corrupt ROM on the new board. I've got to get back to playing the game....thanks again!