I have a problem with my machine - help!

Hi everyone. I have a Bernina artista 200e and it has not been upgraded. The machine has been working wonderful for a long time. Last night while working on an embroidery project a message popped up and said to check lower thread. I checked it and it was fine. I cleared the message and the same thing came up when starting to embroider again. I looked into it further and noticed that the bobbin thread would not catch when the needle went down. I thoroughly cleaned the bobbin area with compressed air and even took the little metal plate off that goes under the embroidery foot and cleaned under it. After all that the lower thread still does not catch and I still get the same message. Any help or advice on how to fix this would be wonderful because I need to finish my project for a customer.

Thanks,
Paul