Water level sensor is a good mod. Head Gasket leaks usually result in pressure in the cooling system but can go other ways

Do see no reason why disc has to be removed. I learned how to do it using what was had at the time. A Land Rover Book manual and a spring scale of the fishing type.

If swivel pre load is out then thars your problem. Note that the 3-4 kg pull recommended above is with the large ball housing seal removed. It is just a trial and error job swapping shims until set right. Each time the pin bolts have to be done up tight. I bend the brake pipe bracket out the...

See the black arrow head symbols in @Dorset_dumpling's diagram above ? They are the earth points and will be on the body, chassis or engine near the item they are earthing.

The hole where the exhaust gas comes out or air goes in from manifold.

The leak to the exhaust is likely only to get worse over time. As a short term repair [ months] you could put in some rad sealant, like Kseal [other makes available] Advertised as permanent repair but in my experience that is not so and will give up eventually. Be careful as 300's are not...

Just out of interest @D1Nut but where does the name "welsh plug" for what we call "core plug" come from. Cheers.

The exhaust port seep could be just a tracking leak from a waterway through the head gasket to exhaust port but the only way to know is head off. Can see other core plugs have been renewed and the heater transfer pipe has been replaced with copper tube. All sign's that engine has spent time...

You put all the shims IN ! ? You may have to re do the swivel pin's/swivel bush's due to them having been set to loose. Swivel pre load involves using the right number and thickness of shims to set the load [ a pull of approx 12fp at the end of steering arm] with no big seal fitted. Land rover...

Swivel housing pre load and tracking to check.

I have said this before but back in the day I recon Land Rover had Man Mountain lean on the nut to do it up as first time removal has been the worst. The locking tab in pic may be non standard but one should be fitted.

The shaft splines and the arm hole are tapered so when nut done up it goes tight, real tight. [ if it was you who removed the arm you will know how tight they can be] The security lock tab is standard fit. There is a master spline and if not lined up arm will not go on right.

You can get an aftermarket one for about £55 and has done its job several times on my rocky coast farm. After a meeting with a hidden boulder it was banana shaped but had done its job protecting things further back.

Don't know if this will help but a couple of years ago my 2a would spin over slowly only if it had a fully charged battery after checking connections and replacing starter solenoid I tried starter with good jump cables direct to a battery bypassing all the landy's original cables, spun like a...

Still have one on mine. It is a standard Land Rover tubular steering guard to protect output arm and steering rod from knocks off road. Mine has a length of scaffold inside. [ met a rock or two in its time] No issue with its removal for road use or light off road driving. @meego link above for...

The folding step is what was/is seen on series safari models. STC7632 is one for defender but should fettle and look fine on series.

Kept fluid topped up as you bleed?

Looks pretty corroded, may be a pin hole leak. ANR2135

This is very likely if there is no slack in the throttle cable.

Wheels are Limestone