Don’t understand how pitman and idler arm work at spec torque settings?

LovetheA's said

The new idler arm tightens down after being torqued so that the foam gasket is just slightly compressed. .................. I’m not able to move it by hand Is there a trick to lining up the castle nut with the hole in the tapered shaft? It is impossible to see it from below based on where it’s located.

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foam gasket..........This indicates the stud is not too deep and is not binding the main part of the arm

not able to move..........how strong are you? it might take some force on a new idler, let's say 20-40 lbs pull like you were pulling on a wrench and that would be extreme, but you SHOULD be able to move it. I'm still leaning towards a DEFECTIVE part

castle nut.......I just "look" at the hole before screwing it together and sort of memorize it, then approach nut tightness a little at a time . If you cannot see it you need something stiff, piece of wire, paper clip, to probe it. Don't you have an inspection mirror? "The old man's friend LOL"