12.7 update failed, uninstalled completely including iTunes.com files tried to reinstall, same result. Did another clean uninstall. downloaded 12.6 same result from Apple downloads. iTunes helper loads but iTunes gets beach-ball and is unresponsive on failed install opens to Itunes Store login splash screen. This is on Sierra 12.6. and it was working fine before I initiated 12.7 update from Apple store. Any ideas on how to make this work short of a reinstall of Sierra. Audio works. Using latest Clover and Nvida GForce GTX 960 with compatible web driver. This is a Gigabyte Z97MX gaming 5 with 16 GB of DDR3 and and I7 CPU with ALC 1150. Samsung 850 Pro SSD 256 GB (dual boot with Win 10 Pro on same model drive of same capacity) I'm stumped... Any ideas or help on how to repair or trace problem???