Hello. HW info: IMAC 27 inch System info: WAS Mountain Lion 10.7.2, NOW back to Snow Leopard. Issue history: Hard drive replaced due to recall issue. Backed up the Mountain Lion OS etc onto an external hard drive using Time Machine. Now can not get the, essentially new, mac to access the external HD. Doesn't find it. SO can not use Time Machine to bring back ML OS and all my data / settings etc. Trouble shooting steps: Tried following steps, all ended up with no result: 1. Reboot holding command+option+R to recovery mode to work from Utility Time Machine. No access. No pickup of external HD 2. Used Migration Assistant 'From a Time Machine backup or other disk'. The spinning search wheel spins and spins and... 3. Unplugged the power cord for several hours and reboot again. 4. Grimaced and scratched. Got sad. Tried resetting PRAM (hold command+option+P+R) but no help. (I know but I am beginning to get stressed. As ever, I am in your shadow as you show me the way. Thanks!