I purchased a new DSL40CR a few months ago. I think I need to replace some of the tubes/valves. The product is still under original manufacturer warranty, so I would like to take it to someone qualified to work on Marhsall amps, rather than change them myself. I have never owned a brand new amp before, so I don't want to void any warranty. How can I locate a proper amp technician in my area (Buffalo, NY) to help me with this? Appreciate any help. Thanks .