[Kennyd]

This is a really bad video, but it shows the general procedure for the 410, 420, and 430 loaders used on 4100, 4110, 4115, 4200, 4300, 4400, 4210, 4310 and 4400 loaders.

Also, the tractor should be in neutral so it can roll easily.

(all the model number given to help with searching for more video's)

Here is the online owners manual: Operator's Manual View

 

[Kennyd]

There should be a bar under the PTO shaft with a hole in it so you can pin that trailer to it, it’s called a “drawbar”, If it’s not there, maybe the previous owner took it off. It looks similar to this:

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[Kennyd]

Pic from JDParts: