S+ display flickering

[rjpohl]

I stopped to work on a guys s+ yesterday and the display was flickering code 21. 
I opened and closed door and the 21 would come back in a few seconds, I replaced the coin in optics and 21 cleared
Then it had a 41 code, open/close door moved to 42 code, open/close door moved to 43 code
Performed Clear and machine came up reels spun and insect coin light was on.
Would not accept coins, I pressed button on the coin in board and 1 coin would register, 2nd press would not register second coin. 
The flickering of of "coins" on display is still present, any idea what caused the flickering?
thanks
Bob

[Jim]

Bob,   sounds strange, has all the symptoms of the wrong SP on the board, meaning it might be a 16 meg board with a sp chip for a 10 meg board ?

or a bad board??

JIm

[Stayouttadabunker]

That is strange how just closing the optic lines causes the reels to error from one to another.I work with 80+ S+'s over the past 20 years and have never seen that.
If nothing has been changed recently regarding chips than what it leads me to believe is that if the game was working fine before, then some IC component may be starting to fail on the MPU.
I'd try a clear first to erase any bad data logic that might be stuck in the system and see if the errors still keep popping up but it looks like you've already tried the clear procedure.
I would try unplugging and re plugging the Molexes in the display panel board...sounds like possible oxidization on a pin.
Did any wire fall off on the deck switches and replugged back in on to the wrong pin?
That would cause erractic problems as well.