Most of the time, E7-03 is not that fatal, like other codes. A restart of the machine usually clears it. The HDD should start back up and work perfectly fine. Could be a number of reasons for it to show that error. Run a HDD read/write test and do a device clone/storage backup, just in case the HDD decides to really pack it in and die. That way, you have all the data ready for the new drive if it is ever needed.
I only install a new HDD if the error cannot be cleared, or if it ever comes back some other day. You will find that most of the time, the error will never show up again.
Restarting the unit cleared the E703 error. But then I got the message "Web Cleaning Unit not installed". Since it is installed I assumed it had reached it's life expectency, so I ordered a new one. However it is also making a loud whining noise (like a jet engine) coming from the fusing area. I was wondering if a malfunctioning Web Cleaning Unit would do this?