Autolite 4100 aid needed

This old carbs throttle return spring is too loose and not allowing the throttle to return back to its original position. I replaced it with a tighter spring and the car would come close to dying under load. I tried to reset the RPM using the throttle screw and it would still want to die. Right now, I have the old spring on it but if I want to make the car's RPMs lower under load, I have to adjust the gas pedal nudging it up from underneath.

Any suggestions?

 

Bttt

 

shaft to baseplate wear?,sounds kinda like it might be.

 

Is this pretty easy to fix? I have a Holley 1850 on the shelf ready to go. I may just swap them out if the ol' 4100 has had it. It's been just recently rebuilt though.