New Holland 2120 issues

[NorthCountryJimmy]

This machine has about 2700 hours of rough use by previous owner.
I changed fluids and filters when I got it.
The hydraulics are sluggish and jerky. The replacement filter I bought online showed up and was far smaller than the factory installed filter. I would like to know what filter might be a better replacement.
Also, I have a couple of pails of NAPA premium heavy duty hyd. oil. Would this be better than the traveller oil in there now?
Finally, I have the loader spool on my bench now. I planned to take it apart and see if it was dirty in there. I have never been in a hyd. spool before. Any pointers?
Thanks

 

[Seven Gables]

First thing I’d do before you tear into that spool is get the correct hydraulic filter from a New Holland dealer. That undersized filter could very well be starving your hydraulic pump for oil , that’s bad. As far as hydraulic fluid you want Transmission/hyd fluid which is rated for use is in tractor transmissions. Do not use regular 32 or 46 viscosity hydraulic oil.

 

[Leejohn]

Check the hyd trans screen, if it has one.

 

[NorthCountryJimmy]

Thanks for the input.
There was a strainer screen with magnets I pulled and cleaned. It was dirty but not bad for a 21 year old tractor with 2700 hours.
I have the (pricey) OEM new holland filter to install now. I have Napa "heavy duty premium" green label tractor hydraulic oil. I took the spool apart, nothing was obviously amiss so back together and will re install it.
I am considering pouring the old oil back in, adding a gallon of diesel, getting everything warmed up and any impurities loosened up and then drain the system and replace the oil and filter with new.