If you are getting the RPS State Error code then your sensor may need a good cleaning. While using compressed air to clean out the headstock is convenient, it can also cause dust to settle on the sensor itself.

Your sensor board is a little green board with black sensors on it. Once you reach the sensor you will want to wipe off any visible dust and debris. But we would also recommend getting a Qtip and some rubbing alcohol and giving it a really good clean all over. Especially in the black sensor parts. Even if your sensor isnt as dusty as the one pictured below, its always a good idea to clean it just to be sure.

While you are there double check the cables and make sure everything is secure.