Allic Chalmers 7060 steering is intermittent

Sooo many things this could be.   #1. When was the last time the power steering worked correctly ?? How long have you owned this tractor??   #2. Did you change BOTH hydraulic filters under the rear end?? and did you use genuine AGCO filters??? I will stop right there until you answer these questions. 

There is 99++% chance the hand pump is absolutely FINE !!  There are TWO filters that require you to get on a creeper to change. I don't think you have done that. The left one must have a screen removed from the old filter you are changing and installed in the new filter you are installing. It takes more than 17 gallons of oil when changing the rear end/hydraulic oil. There are 3 drain plugs to remove. The upper sight glass should have oil in it sitting on the level for at least 15 minutes and the engine OFF. Many sight glasses need to be replaced for being visually cloudy.  You say "everything work fine except the steering".  Have you connected hoses to a disc or field cultivator and lifted it up/down??   Have you picked up a big round bale of hay ??   If not, you don't KNOW if the rest of the hydraulic system works fine or not. And this can be affected by whether the steering system works correctly or not, which your's doesn't. An Owners manual is needed to show you where and how to change those hydraulic filters and only use AGCO filters and nothing else !!!!