Proper function of an Idler Arm?

You say moderate force. I say that may be too much.
Imagine; if you removed the foam end seals,washed out the grease,and flipped the car on it's side, the weight of the arm should flop it over to the downside. Wheels back on the ground,it should have little to no endplay in the vertical direction.After you grease it up it will no longer flop.The thicker or colder the grease, the harder it will be to turn. Those units are nothing but a smooth center spacer inside a bushing, plus the foam seals.They are also available with a caged needle roller instead of the bushing.
The thing is,any non oem tightness in the design, will prevent the caster/SAI from returning the wheel. This is especially so in the case of tight BJs, but the idler will do it too. And the worst part is that the factory caster spec is zero to negative, so that just leaves the SAI; which I cannot recall how tiny it is anymore, maybe 7 degrees,guessing.Cheap parts used to be the worst. When I was in the front end business, TRW and MOOG were the go-tos. I heard they may no longer be.