Try to take some pictures of the hydraulic lines on the tractor with labels as to what goes where.
Then post them.
Take a picture of the way you had the tipper trailer hooked up and post that. Since this all started after you used the rear remotes for the first time I am a bit suspicious about that valve. So also take some pictures of the valve and how it is connected.
Look at your operators manual (can be gotten as PDF from link below). Free but you can give a donation for the storage. Make sure everything is connected correctly and especially that the directional valve is turned fully to the correct direction.
Draw yourself a flow diagram to see how the flow is currently flowing and see if that matches what the operating manual says.
After you put new seals in the pump did you check to see how it was flowing or did you just try to use it?
If you think of the hydraulics just as a garden hose that connects things together that might help. The pump makes the flow and pressure. The flow goes to the block on the side of the tractor, then to the FEL valve, to the rear remote valve and returns to the block, then goes to the three point hitch internally and dumps to the sump. There is not a lot of pressure until a valve diverts the flow to a cylinder. The fluid fills the cylinder end and pressure builds behind the piston and moves the piston. Fluid moves out the other side and back to the valve and dumps into the tractor sump. That is for a double acting cylinder on the FEL. For the single acting cylinder gravity will force the piston back down. I don’t think it will hurt the tractor but I have read very little about single acting cylinders. But there needs to be a tank return line on the rear remote valve.
The directional valve controls flow through the block so is used to divert the flow to the port where your FEL valve is connected to the tractor.
You could disconnect the Hoses from that block and set it back to just powering the three point hitch and turn the directional valve to the correct position and see if it works that way. That would prove the pump is working correctly or not. But there are other ways to prove that the pump is working correctly so I think you should not do this yet.
To check the pump flow, take the line off that is connected to the tractor and provides the flow into the FEL valve. Take it off at the FEL valve and put it into the fill port or a bucket. The flow is 6.5 US GALLONS per minute so don’t run it for long unless it flows back to the tractor.
Did you verify that the hydraulic fluid level is correct?
You should get a pressure gauge of proper range (5000 PSI) and a fitting adapter that will fit into the power beyond port of the FEL valve.
And sorry about the use of non SI units but I don’t know what the metric values are off hand. There were shown in the operation manual at this site
on edit-
@TheOldHokie typed less so beat me to some of the same questions!
