Iron,
Do doubt that your cord is stronger than mine. You have so much more girth. My penis would probably snap off if I would do 18lbs with the RSDT.
Have you tried doing different kind of fulcrums? Like something that is more tall but not as deep, so there would be more bend. You can try longer extensions too.
When I started RSDT I was doing 3x20minx10lbs with no problems.. then I though something is wrong and totally rebuild my fulcrum. After that I could not do more than 5lbs for 10mins.
Also make sure that your penis is not just coming down and then over the fulcrum. That’s why the thing needs to be tall enough to work.
I don’t want to sound disrespectful but looking at your thread in bib forum, looks like you never got the RSDT right or not even the hanger settings. Maybe you just did not post the new setup there? You have not posted in a bib’s forum for a long time. Again, I don’t want to start a argue but reading at your thread, it looks like you never got it to work right.
Also, how many sets per day and for how long did you do? Did you do it every, be honest?