A happy ending... for now.
Been troubled with a slight misfire for ages now.
Done so far, PCV, cleaned EGR and MAF. No difference.
Thought it was low coolant temperature so fitted Renault 5 stat in line, got a real one to fit at some stage.
Then worried about engine temp going over 105 deg before dropping back to 90 ish.
Tried Millers and TSO, they seemed to help, but...
recently misfire got worse, found out No 2 injector, removing plug made little difference to running.
So, started reading horror stories of smashed covers trying to get them out plus the cost of new injectors.

Contacted Gap Diesel Solutions and they had a refurb injector for £102, which arrived next day.
I read somewhere that getting the engine up to temperature before removing is the way to do it.
I had to remove the inlet manifold to get access to the bottom of the injector.
Undid the 2 nuts on the injector collar, put a piece of wood on the plastic cover to protect it and levered carefully with a chisel under the fuel inlet bit of the injector and it just slid out.
Refitting was easy and engine started on second turn of key and sounds like new and drives beautifully. Also the engine temperature has not been over 95 deg.
Hope this helps someone to tackle this job.

I have a spare engine and cannot get the injectors out, going to have be inventive if no one has any ideas

Other than plenty of penetrating oil around the base of the injector and a heat gun on the base for about 15 mins to get it warm and a thin lever, possibly a crowbar, under where the fuel pipe connects and leaver upwards carefully, then no!

While doing the above job I was curious that there were pools of oil in the top of the engine. When I removed the injector they ran down the injector hole.
As there is only a rubber seal to create a seal I wonder if that oil is getting past older seals and causing the classic blue smoke on start up.
Anyone found where the oil is coming from and how to stop it. I have tried to mop it up but it keeps coming back.
Any thoughts?

I have just replaced the injector wiring loom and noticed oil around the base of the left hand injector (looking from the front of the car).
I ran the engine with the black plastic injector cover removed and a small amount of oil was being blown out of the left hand injector cover mounting bolt hole.
If yours is doing the same, this could be the source of the oil but I don't know if it's normal or not.

Yes, I found that out the hard way, it needs a fibre washer between the cover and mounting hole. The puddles I have never seem to get too deep so I assume they drain somewhere? Down the injector holes I presume? But where it comes from is still confusing?

it is normal you need to put that bolt back in and never ever leave it off you may have diesel leaking from the bottom of the injector if this is the case you need a new copper washer