I didn’t even have to use the "magic word." It was Bill Murray’s idea for me to try on a proton pack.

In the middle of an interview on a busy soundstage during shooting last September, Murray signaled to one of the prop masters. “You think you can do me a favor?” he said. “Can you get the heavy pack? And put it on Anthony? Let him wear it for a while. I don’t think he understands exactly what it’s like.”

There was a pause. “Seriously?” asked prop master Ben Eadie, the Ghostbusters’ armorer.

“Yeah,” Murray said. “Seriously.”

Out of respect for spoilers, I can’t tell you what was happening around us or even who else was in the scene. But I can tell you we were in Canada on the set of this summer's upcoming Ghostbusters: Afterlife, and Murray, just days before celebrating his 69th birthday, was determined to show a visiting journalist that bustin’ doesn’t always make you feel good.

“When you put that gear on, it’s so uncomfortable. It’s so heavy, just to stand there with that weight on your back, tilting your spine,” he said, rolling his eyes at the memory from 36 years ago. “And we wore them for a long time.”

That’s something he especially liked about the new movie, directed and cowritten by Jason Reitman (Up in the Air, Juno). Newcomers are shouldering the movie this time.

Ever since the new project was announced a year ago, fans have wondered if the stars of the earlier films would return, and tidbits of news have been leaking out sideways. Murray was definitely on the set at various times during that week last fall, as were Dan Aykroyd and Ernie Hudson, reprising their respective roles as Peter Venkman, Ray Stantz, and Winston Zeddemore. Also visiting the location during those days were Annie Potts the long-suffering receptionist Janine Melnitz and Sigourney Weaver who played frequent malevolence magnet Dana Barrett. (Rick Moranis, who was accountant Louis Tully in the original, has largely withdrawn from performing over the past 20 years and did not return.)

Exactly how the originals will figure into the July 10 release will be left for the film to reveal, along with how the narrative deals with the absence of Egon Spengler since actor Harold Ramis, who cowrote the original movie with Aykroyd, died in 2014. “Well, we are a man down. That’s the deal,” Murray said, pursing his lips, looking down. “And that’s the story that we’re telling, that’s the story they’ve written.”