M372 Hydraulics issue

[andyroo33]

Hi all,
New to this tractor lark, was quite pleases with my purchase of MT372 with loader.
all seemed to work fine but all oils were in terrible state, so thought change them.
Couldn't do engine drain plug solid, drop sump at future point.
Drained Transmission and refilled with Universal Tractor Fluid, then loader and 3pt started playing up.
Would move in jerky movements, and then not at all, what have I done wrong?
By cracking the odd line I seem to have fluid where its needed.
Read in this forum, to use UTF but another said 80 gear oil??? which is correct?
Another post said possible crud in the 3 point valve or the relief valve. As I don't have a manual can someone point me in the right direction?
Thanks in anticipation

 

[Gunny]

Did you drop and clean the transmission filter?

 

[andyroo33]

I confess no I didn't, couldn't identify it, going to have another look for it now I have researched

 

[andyroo33]

All done and that worked, thank you very much.
Filter was absolutely filthy.
Didn't think it would have stopped what was working, but I bow to your greatness, thank you again.