Hi all, apologies if this is a repeat of other threads.

My power steering was playing up on my 90 300 TDi , to the point where you just could not move the steering wheel. Ended up fitting a new pump and low pressure hose from pump to reservoir. Started up the engine and fluid spewed out of the reservoir, however that calmed down, I think I may have overfilled a bit?? While still on the jacks engine running, turned full lock left to right and bled the steering box. Everything seemed fine turned really easy and smooth. Once it was back on the deck and ready to drive away, the steering went like it had before, stiff to the point of not being able to turn. I went forward and reverse a few times, still the same. I have even greased up the steering UV joints which seem fine

I am at a loss now, any help much appreciated. Sick as a chip not being able to get out and about in it!

Put it back on stands, remove steering arm and move the wheels by hand. See if they are stiff to move

You can't grease the steering ujs and you can't tell if they are OK by looking at them.
Try soaking them in wd40 and see if it gets better.
If it does then still change them, if not, you will have to remove them and see if they are working.
Does sound like classic steering ujs at fault but you will have to diagnose.
That is assuming that 300tdi still has the old style ujs, not sure if they were ever changed.

If just recently changed my ujs as I could feel a little play in the bottom one, top seemed lovely. On removal the bottom one was a little worn but the top one was solid (by hand working) in one plane and notchy in the other plane. Steering was still light though and no noticeable difference when 2 new ones fitted.

I got the two joints via eBay from foundry4x4 both bearmach.
Remove all the bolts on the joints completely as they locate in a groove on the shaft and the joints won't knock off otherwise. You'll need to knock the top joint up to free the bottom one off the box then knock the top one off the stubby column.
Wire brush the 4 male splines clean and give them a good smear of copper grease. This will make reassembly really easy I found. Don't forget to line up the grooves with the bolt shanks!

Tell a lie, it was LR parts on eBay, it was the drop arm I got from foundry4x4.