Hi,
Nice to meet you! I'm Randy, an Independent Advisor.
Code 43 with older iPods usually comes down to the cable, drivers, or Windows USB recognition. You can try this, First, make sure your replacement cable is a true sync+charge cable, since many third-party ones only charge and will trigger Code 43. Second, in Device Manager uninstall the iPod entry (under Portable Devices or USB controllers) and then reconnect it so Windows reinstalls the driver - also confirm that Apple Mobile Device Support is installed alongside iTunes. Third, try different USB ports and, if issues persist, reset the USB stack by uninstalling the USB Root Hubs in Device Manager and letting Windows rebuild them after restart.
Kind regards,