Without a hitch- replacing the HD of a MacBook Pro 13" 2010
The original HD stopped booting up in my MacBook Pro 13" mid 2010 vintage. I spent weeks off and on testing the drive and software with Mac's disk utility, reformatting the disk, reinstalling the opsys, etc., without knowing that the solution was quick and inexpensive!!
After recovering important data (by booting from an external USB drive), I discarded the old HD and got a very cheap exact replacement from iFixit. Following crystal clear instructions it took me less than 5 min to replace and restart the Mac. I installed MacOS Sierra from a USB installation drive I had created earlier and was booting from the new HD in less than 35 minutes after replacing the drive.
Later I realized that I should have taken this as an opportunity to upgrade my MacBook with a solid state drive. They offer many advantages over a classical mechanical drive and nowadays they don't cost an arm and a leg like they used to... At the time I replaced the old drive I was only troubleshooting the problem. I wasn't sure whether it was the drive or other parts of the hardware. But if you are sure your problem is a faulty HD, go and buy an SSD to upgrade your Mac.