IGT S+ Weird Problems I'm Stumped

[AcePeter]

Hello I have an IGT S+ that keeps throwing a 43 ( Reel #3 Tilt) and 21 (Coin in Error) code. I have checked with known working main boards and known working reels and it still throws the code during game play. It happens intermittently it can play for 10 minutes to an hour then the code 43 and sometimes code 21 comes up. I have checked pretty much everything mentioned about these codes in other posts about solving these codes. Any other suggestions about what it could be? Bad reel harness? Bad power supply? I'm kinda at a lost here. Thanks for any tips.


Turned out to be bad coin optics, The optics would work at times but needed new ones, all good now. Once I changed them no more 21.
Thanks for all the help.

[sixcardmark]

Intermittent "open door" could cause those errors.  Make sure door lever is all the way down and check all switches on door circuit.

[AcePeter]

Thanks, the latch is all the way down and the optics seem to be aligned. I was playing it and the code 21 came up and the reels spin continually slowly when the 21 error shows up. I clear the code but it comes up after a few spins.