I have an HP scanjet 7450c scanner with ADF, it worked fine until the warranty ran out, now everything scans to a black screen. I have done all of the diagnostics suggested by HP support, and then they told me it is "likely" a hardware problem, and suggested I "upgrade" to a newer machine. Well the comparable machine is about $600.00 or more, and I think I should be able to fix this one for less than that. Oh yeah, actually, I replace hardware all the time in my computer, why can't I just replace something in my scanner. Can any one tell me the proper way to diagnose scanner hardware to figure out what I need to replace.