Hi guys! Welcome to the forums! The last popup I replaced cable on was a 1970's vintage Viking, back in 1986!
Here is a link to a bunch of Youtube videos
. From what I recall we had a broken cable and we taped the new cable to the old cable to pull it through. I do remember the ends were swedged on, had to borrow a swedging tool. We bought a big spool of cable and the fittings and made our own as we went along. I also remember we got the top up and had it blocked with 2x4's.
Good Luck and let us know how you make out!