need assistance on Cat backhoe hydraulics

Hi,

I have a cat 426b that the rear stick control lever was getting difficult to move and finally just froze up. I pulled the spool out of the valve body (did not come out easy) cleaned the valve body (still on machine) and put spool back in but it is still binding. I am not very knowledgeable on how the spool centers and responds to center. Also looking for thoughts/ideas directions on what I can look for in the body that could be restricting the spool from moving. Or could it be the spool itself?

thanks

need assistance on Cat backhoe hydraulics