The surface on the slide that mates with the slide stop lever catch has some rough spots including the finish. Give a little polish to it, then a dab of grease and the slide will close nicely upon pressing the lever with your thumb. I lightly hit it with some 800 grit emery then used the small wheel on the Dremel with some Flitz. A few seconds is all that is needed. You can also raise the slide stop lever and give a buff on the lever catch too. Both polished surfaces decrease the friction.
I usually just sling the slide but this is a nice option to have handy. I image over time it could fatigue the lever but it did make a noticeable difference
Good Luck and straight shooting,
Tom