Hi again michaelh40
You didn't answer the question, "Do you have any problems stopping and pausing live programs, and then playing them back?" (This helps determine if it is indeed a hard drive problem)
To factory reset go to Settings (the cog at the end of the Home menu) > System > Factory Reset. It's actually misnamed and only a partial system reset and not a complete factory reset. You are given 2 options
Keep Recordings
Format Disk
Select Keep Recordings, which means you won't lose your recordings, and any planned recordings, or series links you've set up. You may have to sign into your apps such as iPlayer, Prime, Netflix and ITVX again.
If you still have issues losing recording then try again bit select the second option Format Disk, however this will remove all recordings, planned recordings and series links.