I know this thread is 8 years old but I'm really glad I found it.
Thank you to the original poster and all the responses. I have a 1-1/2 year old Shield Plus PC that has run flawlessly since day one and it has eaten about 700 rounds since I bought it.
Last Sunday I put a quick 50 rounds through it. When I got home I was going to clean it as I always do. For the first time since I owned it I could not remove the slide. I resisted the urge to force it and went straight to the computer and Google. It brought me here and I immediately performed the three-handed spring re-seating procedure and got the slide off.
I was very tempted to re-seat the spring with a punch like the OP described but the ragged looking condition of the spring had me concerned. When the slide was stuck the spring was pointing up and toward the rear of the gun so it was likely bent too. I was going to atttach a photo but it looks like the photo has to be on a hosting site??
Since Smith has a lifetime warranty I decided to call them. I had a first-rate experience with their customer service, with about a one minute wait time at 11:00 on Monday morning. The guy was polite and quickly took my information to send me a pre-paid return label. The surprising thing was that he asked if there was anything else I wanted to have checked while they have it. I told him actually yes, there was. I told him that I was a little disappointed with the trigger because I was hoping that the Performance Center version was going to be smooth and crisp. Mine has a gritty feel in the initial take up if my finger isn't 100% square to the trigger. With any pressure at all to the side. the trigger feels gritty.
The service rep said he would add it to the work order.
I am shipping it with the slide off so they don't have to go through that exercise again.
So, its on it's way to Tennessee tomorrow. I'll keep everyone posted on the outcome.