Don't Just Dive In

My Problem

The Hard Drive in my mid 2010 27" iMac went out. I did have a WD external HD Time Machine back up.

My Fix

Opening the iMac, removing the screen, R&R the HD went OK....but

My Advice

Be sure you have an external bootable drive to set up the new HD! I thought you could Command-R and set up the HD from an online Apple source. NO, you can't. I had to borrow a Mac laptop from my daughter to make an external bootable OS disk. The easiest way is to use a program called DiskMaker X 4b4. After I set up the OS the Time Machine restore was easy.