I went through 5 or 6 Dual Scan IVs over my 35mm career... I would just buy spares whenever I saw one under $100, at one point I owned three at the same time. Love the scan quality but their guts are junk. That said, like a wayward brat, sometimes letting them cool off/discharge static for a day and/or a sharp wack will set them straight.
FWIW the power supply and film carriers still sell for high prices on eBay so don't pitch them! Many electronic resellers sell Dual Scans without any accessories so people need those pieces to make a working scanner.