I'm guessing here, the top link driven in pins are installed so the threaded rod ends cannot separate and
drop a three point implement.
I have WSM's (work shop manuals) for my machines, and significant experience as a former auto/truck technician, along with tool & die/model shop machining career experience.
I still go to the Kubota website frequently and look at the parts exploded views for my tractors.
Sometimes it helps understand how a particular tractor system operates, or how to take it apart for service/repairs. I suggest you become familiar with that process.
I was doing a recent BX restoration and just couldn't figure out how to remove the entire assembly for setting the mid mount mower adjustment height. Even after looking at the WSM and the Kubota website parts exploded views. However, I did find a YouTube video showing me exactly what I was attempting to do, right down to what size metric deep socket was required. YouTube is another option in the toolbox.
Do you have a WSM for your L 2501?
If not, download an electronic copy here for free!
Over 600 free Kubota manuals. A library of free manuals and parts diagrams compiled by Kubota tractor owners. All free to download instantly. No tricks, no subscriptions, no sign ups, no weird apps or software to install.
kubotabooks.com
I just checked, they have both, Owners/WSM.
I have owners manuals in electronic format on my smart phone for when I'm away from the computer.