As we're a small design studio, we don't keep replacement parts or instruments in stock, nor are we able to offer instrument repairs.
If you need help with Rock Band 3 hardware, contact Mad Catz customer support for troubleshooting and warranty claims. This includes keyboards, battery covers, the Mustang, dongles, drums, guitars, and the Pro MIDI converter.
Web support: http://support.madcatz.com/
Email support: email@example.com
Phone Support: 1-619-683-2815 OR +44-(0)1454-451900
If you need help with Rock Band 2, Rock Band (1), or The Beatles: Rock Band gear, please contact EA customer support for troubleshooting and warranty claims.
EA Web Support Portal: http://customersupport.ea.com/loginapp/rockband/rockband_portal.html
If you are outside of warranty, you can search online retailer and resell sites to find replacement parts, such as eBay or Amazon. Please note that Harmonix does not have any affiliation with these sites and cannot guarantee anything purchased secondhand.