If you want to pull another cable:
- secure a string to the old cable
- pull the cable out the other end, pulling the string through
- secure the string to the new cable
- pull the string out the other end, pulling the new cable into position
Back in my day the local telephone company used waxed lacing cable for that sort of thing[1]. These days it seems that polypropylene string is popular (search on "conduit pull string").
You basically want something that is slippery and will tend to not get stuck. I have used Dacron fishing line, but that is mostly because I had a bunch of it laying around.
The sell pulling string in the electrical section of the hardware store.
AKA boy butter [0].
Excuse me to hijack this comment adinisom.
I wanted to reach you regarding your comment here: https://news.ycombinator.com/item?id=44547866 Would you be willing to maybe elaborate on the problems caused - I've planned to adopt Miro Sameks for an application? DM me via my about me, if interested. Would be very thankful.
Pull a string alongside the new cable, too, and tie it off on both ends. Always leave a pull string in the conduit.