PS4 drive not accepting disks

I have a PS4 which I bought as faulty - it would power up and take disks but no hdmi - I replaced the HDMI port and it worked fine but the drive took disks slowly so I thought Ill clean the drive. Since doing this the drive will only take disks in if they are partially in the drive when you power up. If you press the eject button it spits them out fine - but try to put them in when powered up and nothing happens. Power down (or put to standby) push the disk in - and power up again - it takes the disk in fine and plays normally. I have tried replacing the large ribbon cable but that has made no difference.
Any Ideas please?