Machine plays Analogue fine (just to test 
). Digital tape gives no output whatsoever, nothing on the VU meters at all but the machine does find absolute time and does know where tracks are as it will happily search and start to play next track, however it will not show title or track info on retail pre-recorded tapes. If you press text button while playing, the display will just continue to say “reading”. Service mode gives F0 FFFFFFFFF 
So far I have:
DCC900 swapped boards PZ03 and PW03 with known good re-capped boards from Marantz DD82 & issue remains.
Swapped tray/servo PCB PM03 and made no difference.
I have measured the head coils and found all read heads to common measure around 49-51
and the write coils are all around 3.5so to me this indicates the head and the ribbon are in good order electronically.
The head itself does not look as good as the head on my Marantz, I have scrubbed and scrubbed with IPA but it never looks any better. I am thinking the head maybe too far gone? But I would imagine I would get a least a glimmer of output every now and again if this was just a dirty head issue?
I have also put complete transport from Marantz into the 900 and it plays perfectly so this rules out everything outside of the transport itself such as the motherboard (PG03) & AD/DA (PA03).
I really don’t want to risk removing the head from my Marantz & swapping it with the Philips just as a process of elimination – I could end up with two players with issues!
Does anyone have any ideas? There is a small PCB under the transport that appears to have a tacho on it and unless I’m missing it, I can’t see any info on this in the service manual? I think it is pictured as J071 on page 95 and has sensors Q071 & Q072 mounted on it which are for take up and supply tacho’s.
TIA 
Spot on