How do you fix a case 1840 skid steer no power lifting bucket?

If you need to rev up the engine to get power in the bucket you may have a worn out pump, otherwise something may have gotten into the system and possibly blocked up the safety bypass valve, that would rob all your hydraulic pressure.

If you replaced a hose recently it could be foreign matter, OR the hose end was crimped too tightly and the flow is reduced drastically.