which pin are you referring too? Can't really go wrong with the pins but my guess is the original might have gotten damaged and replaced by the shop?
That pin has two groves on it that locks itself inside the locking block. If it is loose then that means they didn't put the gun back correctly.CYM it's called Blocking Pin. It's right directly above trigger. There's a small one & a big one . The small backed almost out after shooting 40+ rounds. I had to take my knife out and knock it back in.