Code 41,42,43 are pretty common.
You can cause this by a loose reel strip rubbing slightly on the glass ..... touching the wheel during a spin etc.
There is a clear procedure for these errors, see Ricks FAQs on the main page.
If it does not immediately clear try swapping Reel 1 with Reel 2 and see if the problem moves with the reel or remains. If it moves then its something to do with the reel motor, assembly etc. If it stays its with the MPU.
You can also check out the 5 resistors on the top left corner of the board 3 will show signs of heat, 2 will be pristine - the S+ could be a 5 reel slot, if the first resistor looks totally fried you can replace it with one of the two clean ones or at least read its value (because they are not burnt) and replace in kind.
There are also reel driver chips that can be replaced - but lets get you through the above testing before we go hunting for ghosts.