8n hydraulics

I was on before with my 8n lift not lifting up.I took top off changed fluid noticed that when I had side inspection cover with dip stick off I could lift quadrant and the lift would come up a little and stop, I could take a piece of wood and pry the lift arm toward the front of the tractor and lift would go up and vibrate and jump. any ideas out there what I need to do next, is it the arm bent or a valve or what?

Gary,I would say that the lift control lever going to the pump is bent,and needs to be straightened out.

(quoted from post at 16:31:17 02/27/17) I took top off changed fluid

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If by "took the top off" you mean you removed the hydraulic lift cover from the tractor, what did you do to it while it was off? You didn't need to remove the lift cover to change the fluid.

(quoted from post at 16:31:17 02/27/17) I could take a piece of wood and pry the lift arm toward the front of the tractor and lift would go up and vibrate and jump.

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By manually moving the control arm forward you were manually moving the valve of the pump. Your hydraulic lift cover may just require adjustments. There are a series of adjustments on the 8N lift cover. Some are external, some are internal to the cover. As far as "is the arm bent or a valve" The arm may be bent - common on these old tractors. a visual inspection of the arm will tell you if it's bent. I doubt the valve is bent. Pretty impossible to have that happen. If the valve wasn't working properly, the lift wouldn't move when you manually moved the valve with the control arm.

(quoted from post at 16:31:17 02/27/17) lift would go up and vibrate and jump.

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Not quite sure what you mean here. If the lift arms on the tractor were jumpy, that could be air in the pump from not working and or changing the oil. Several motions of up and down would clear out the air. You need to look at the lift cylinder under the lift cover while lifting something with some weight. See if there is fluid leaking out of the cylinder. If so, you are in for a rebuild & adjustments.

Yes, control arms do get bent. Here is an example.