Picture of Throttle Body and the 2 Jubilee Clips to remove
a section of Intake Trunking from the Throttle Body



Remove the Larger Breather Hose. (2 clips)
Remove the large black intake trunking that connects on to the Top
of the throttle body. (2 large jubilee clips)
Remove your IACV. (1 electrical connector and 2 bolts)

Follow the Smaller Breather Hose until you find where it connects
to the Jet, just below your throttle body, between the throttle
body and the engine.

Picture of Jet that the Smaller Breather Hose Connects to.



Use some long thin pliers to compress the ends of the clip securing the Breather
Hose to the Jet, and use a flat bladed screwdriver to gently lever the clip back  
along the Hose away from the Jet that it connects to.

Now put the pliers around the clip and gently wiggle the Hose whilst levering
between the end of the Hose and the Jet with a flat bladed screwdriver
until you've removed the Hose from the Jet body. Don't try just pulling the Hose
off, as it may have stuck to the Jet and hardened and will probably break.

2 water pipes connect to a Banjo Joint that swivels about the Jet.
So you've no need to disturb the pipes. The Banjo, with the 2 water pipes
still connected, will just hang roughly in position when you remove the
Breather Jet.
There are 2 metal sealing washers either side of the Banjo, that seal when you tighten
the Jet into the Inlet Manifold below the Throttle Body. So don't lose or damage them
or you'll end up with a coolant leak.

Unscrew the Jet using a normal spanner, bit slow this, as it's a 'flat at a time' job,
and then you need to reposition the spanner.
Watch for the metal washer between the Banjo and the Inlet manifold as the
Jet unscrews. It will probably loosen and drop down off it's land and onto the Jet
as a gap opens between the Banjo and the Inlet manifold. If it does, loop a piece of
wire or cotton thread through it to stop it dropping out of sight into the depths
of the Manifold assembly before removing the Jet completely.
When you remove the Jet, ensure that you also have the other metal sealing
washer that fits between the Jet nut that you've been unscrewing and the Banjo
coupling.
You may get a little coolant flow from the Banjo when you remove the Jet, but
we're only talking an egg cup full here.  

Once out, I don't drill the Jet, I stand it on end and fill it with Carb Cleaner.
Let it soak and keep prodding it with something thin and pointed, like a darning
needle or something similar. As the carbon softens, you will eventually break
through, and then you can clean it out easily.
Remember that the Jet is shaped inside like an Hour Glass Eggtimer.
So it narrows right down to 1.6mm in the centre. So don't try and
push anything through it larger than this.

These Jets are calibrated to give the correct flow through at Idle. If you drill it
and get it off centre or the wrong size, you will widen the jet and then get the
incorrect airflow through into the engine at Idle. This will give you an unmetered
airflow, similar to a split vac pipe.

When you refit it, ensure that the metal sealing washers are seated correctly
either side of the Banjo joint, and sitting correctly on the Breather Jet lands.
The one in between the Banjo and the Inlet manifold will keep trying
to slip off. So I found it useful to hold it in position with a small flat bladed
screwdriver, on the Jet Land and against the Banjo coupling, whilst tightening
the Jet back into position.

As the Jet starts to bite into it's final position against the Inlet manifold, the friction
between the Banjo and the sealing washers will try and spin the Banjo in the
direction of tightening. So wedge a large flat screwdriver blade between one
of the Banjo water pipe connections and the Fuel manifold to hold it in position
during the final tightening. This will hold the Banjo and pipes in the correct
position and not put them under a strain when fully tightened.

Clean out the small Breather Hose.
Wiggle the Breather Hose back onto the end of the Jet, and then refit the clip,
again using the long thin pliers and screwdriver to aid positioning it correctly.

Don't forget to check for any water leaks from the Banjo when you run the engine.
Best to find out now rather than 100 miles up the motorway when you start
overheating due to lack of coolant.
Check and adjust Coolant level in Header tank as required.

Clean out the Large Breather Hose.

Continued........Please do not add to thread

The following pictures were kindly provided by mkaminski100.
They show the Breather Jet removed and the small size of the internal jet that you are unblocking.