My external is making a faint tick, tic...

I am sorry to inform you that your drive is failing. Normally drives will start with a faint ticking then move onto a solid clicking sound and maybe even a grinding noise. You will need to backup all of the data on that drive and then download the diagnostic utilities from your drive's manufacture and run the testing tool. If you can hear any ticking there is a very good chance the drive will fail the diagnostic tests. Assuming it fails you will then be able to RMA your drive for a working one as long as it is still under the warranty period. If your drive passes all the testing from the manufacture's tool I would advise you backup your data from that drive regularly and run the diagnostics weekly until it throws and error code.