Disk drive not working

Hi all,

I have a really odd one. My disk drive has stopped working. Nothing odd about that? But here are the symptoms:

1. Wont take a disk in (but once in a while it will like one in 40 or 50)
2. Stripping down the ps4 and the mechanism is fine, rollers are clean and in position
3. Manual eject screw works fine and takes a disk in.
4. If there is no disk in it beeps three times as per normal
5. If I manually insert a disk and power on it beeps once but does nothing
6. I can hear very faint click about once a second, a bit like if you have a mechanical external hard drive which is not quite getting g enough power to spin
7. With the disk in and powered on it doesnt seem to read.

Any advice would be most welcome. I suspect a bad ribbon but cant see why the cable would suddenly just give up. So worried it is the mobo

Magnus