Hi, I have never had a steering hand pump apart. With engine off, you should be able to manually crank the steering wheel left or right and it should turn the front wheels but if it is 4WD it will be difficult and if you have a loader you can lift front wheels off the ground and the wheels should turn easier. I would do some more diagnostics before removing the steering hand pump like removing the lines to the front steering cylinder and point them into a clean bucket and with engine off try turning the steering wheel both directions and see if hydraulic oil comes out the PS steering pipes. If you have the pipes secure in the bucket then you can start the engine and move the steering wheel and hopefully blow the dirt out into the bucket. Hopefully front steering cylinder is not plugged.
Re the hydraulic system diagram is not 100% correct for 3230/4230 series as CIH redesigned the range transmission to make a better hand brake system, T/A and the drive shaft for front wheels comes out the bottom center now instead of the right side.
I am not sure if the T/A pump is still present or if it runs off the main pump now but the T/A is now controlled by an electric switch on the left side of dash. Somewhere I had the details of the update but cannot find them right now. Also there is no more transfer/lube pump low pressure warning light on the dash.
Re steering hand pump from an experienced IH mechanic,
"The 74 and 84,85,95 series, use a Danfoss steering valve. You have to remove all the valve from the tractor and open the valve to change the seal. Some parts inside have to be timed, so if you haven't opened a Danfoss valve before, good luck. Best way, to take the valve to a CaseIh dealer and ask to change the seal. To install the seal, you need a special tool. Be careful when you remove the steering wheel, don't hit the shaft with a hammer, remove the wheel with a puller. I have done many seal change when I have worked for CaseIh dealer." Benard le mencano
I will also look for info on transfer/lube pump.