Why is there so much fear surrounding this? I mean I walked into it with a relatively sound mechanical understanding of the apparatus, and when I put it into practice I only used as much suction as I could without any sort of unexpected discomfort.
As far as a pump getting stuck on you, well, i mad the mistake ONCE during my latest venture of sliding out the tubing that I used to draw/bleed off vacuum pressure and yes it got "stuck" and it was uncomfortable because I did not have complete control of the pressure going on, but let me tell you what I did.
I did not panic. I was uncomfortable, but I realized that all of the spongy engorged tissue around the base of my dick was soft enough to slide a lubed finger under and bleed off the suction with a tickling vibrating flapping "fart" noise, haha.
Based on my limited knowledge and experience, pumping does not necessarily require immense levels of vacuum pressure to be successful. i mean, if you are in any danger of ripping off your testicles or dick, then you are probably using more vacuum pressure than you should.
TL;DR: If you're worried about tearing off your genitals "ur doing it wrong!"