I have 2 external HD's for backing up on Time Machine. Recently it stopped working because my 1T HD was full and it wasn't deleting old back ups. One HD is 1T and one is 500g. Now I am getting a message that to back up the latest I need over 500g for it and it only gives me the option to use the 500g HD that has 485g of space. Im stuck on what to do. I have tried to delete the older back ups manually and of course that takes forever. My 1T HD has only 26g left of space, my 500g has 485g of space. I haven't had a successful back up in weeks. 