Shaft sensor error

Hi everyone,
I own a Toyota ESP9100 - a really awesome machine. But one month ago i've got this error - SHAFT SENSOR ERROR. There's no Toyota service in Bulgaria where I live so I will really appreciate every help or advice.
AND... the machine stops moving frame at some point (but still embroidering the same place), the counter of stitches on the LCD screen also stops. Change speed slider and STOP button does not function correctly too. Their operation is delayed 20-something seconds!?

This is the link to pictures with a some description of the problem with my machine.

https://plus.google.com/photos/114304608407444032053/albums/5761981842869253505?authkey=CKzczMjakb3DcQ

I'll be happy if we quickly identify the reason for this error and the strange machine's behavior.