Kubota has good dealer support, parts available world wide (helps keep prices in line. You have choices if local prices go up).
That said, Kubota parts have always been very reasonable, compared to Yanmar and Volvo.
I haven't worked on the other brands, and have only worked on Kubota Diesels in...
Turn every thing on the ditch witch off.
Be sure the battery is fully charged. Check acid level. Fill if needed.
Loosen the hot wire on the battery.
Rub the loose hot wire gently on the hot terminal, to see if it sparks. This is best done in a dark place, or at night.
If you get a spark...
As Mike said, it sounds like air in the lines.
If there's air in the system when you fill the reservoir, it may take a while to work out of the system.
Go to full lift on the loader, then all the way back down. Check and fill the hydraulic oil.
Run the 3 point full up and full down several...
Newbie in BC, Canada.
Just found this group. You already gave me great advice to fix a leaking battery.
Good, solid, down to earth advice.
Thanks! I look forward to more of the same