I recently had the issue with my Royal Flush. Everything had been working fine. Next day, not so much. Reels went through the reset stages but the motor kept running.

My issue was one mis-aligned score reel.
Here's my suggestion for the day. Put points on each reel for each player and reset the game. For me, it's quicker and more fool proof than a visual inspection. Mine was the Player 2 Hundreds reel.