What is the model of your loader. LA1153 is shown in my loader shop manual as being for a M5040.
If it is this model, do you have the detailed spec's on its performance which covers a full page? If not I will find a way to get it to you.
First you need to spend about $35 to buy a pressure gauge and hydraulic fitting which will plug into your rear remotes.
My comments below flow from owning a M7040 which may or may not be the same design as your M5040. Below is material from an earlier post of mine.
I have some info owner's of M7040 with FEL may find interesting.
I was having trouble lifting my large heavy snow blower (when the blower was covered in snow and ice) on the 3pt hitch in spite of using the lift arm holes which provide the greatest strength.
My shop manual provided instructions for setting the 3 pt relief valve which is located near the rear remotes.
I bought a new gauge and hydraulic fitting to plug the gauge into a remote port. Total cost for the gauge and fitting was approximately $35 which is a great investment
For the test the tractor is to be run a full revs and then the remote valve activated and a reading taken from the gauge.
In spite of adjusting the relief valve to its maximum position, I was reaching about 2,400 psi which is approx 400 psi below the 2,800 psi setting in the shop manual.
I spoke with the dealer's mechanic some time ago about this and learned that the FEL relief valve could be the cause.
My health does not permit me to crawl under the tractor so I had the mechanic come to my place this week for the 300 hr service.
First he double checked the reading I was getting on the remote and then began to adjust the FEL relief which you access after removing the metal guard around the FEL valve.
Soon the remote valve was reading almost 3,000 psi.
He explained the hydraulic circuit this way.
The pump has two sections. One feeds the power steering and has an independent hydraulic circuit. The other section feeds first the FEL valve and then through a power beyond port the flow goes to the rear remotes and 3 pt. If the FEL relief valve is set below the factory 3,002 psi the pressure available for the 3 pt and rear remotes is reduced.
The workshop manual for the tractor does not show a hydraulic circuit for the FEL and the shop manual for the FEL is, for my level of knowledge on hydraulics, not informative enough about how the two systems integrate once on the tractor.
Now the curl cylinders will lift the front wheels of the tractor perhaps 6 to 8 inches off the ground whereas before the relief valve was adjusted this was not possible. Lifting the snow covered blower is no longer a problem.
Here is the section of the FEL shop manual dealing with setting the relief valve.
The following picture of the shop manual page is too wide for what is normally posted and requires scrolling your screen sideways to see the whole picture but I was afraid to resize if for fear of it being hard to read.
Don't do this without a new gauge of the proper range as you can easily damage your tractor or hurt yourself. If you have doubts spend the money on a Kubota mechanic. Setting the two relief valves takes just a few minutes.
Dave M7040