I left a USB stick in the front USB port of my Tyros 2, and after a period of time the USB port failed, the moral is do not leave a stick in place, but remove it after use. You can purchase a new USB Circuit Board from Yamaha UK telephone 01908 369261 they are extreemly helpful, the circuit board is listed under part number 6015 and item number 156779-001 WE81750OR, the cost is £10.91 plus handling £3. To take the Tyros 2 apart turn the Tyros 2 upside down and remove all the screws situated around the outside of the case, then remove the screws 7 in all, situated deep in the centre of the base, carefully turn the Tyros 2 back onto it's base, and then carefully lift off the top cover, sliding it slightly forward to clear the piano keys, then lift the front and carefully place it upside down on over the base section. you have now exposed the ineer workings of the Tyros 2 to enable you to carry out any repairs.