hi, i love my hitman but cant figure out how to get it to spin longer.
Practice to get a stronger, straighter throw. There isn’t much more to it.
Are you a beginner? If you are, just work on stronger throws. If you’re not, and you have been playing forever, then you can try siliconing the o-rings. Have you broken into the bearing yet? If you haven’t, you might wanna try cleaning the bearing.
QFT.
Besides throwing, you can try to silicone it, and widen the gap or throw in some shims. But without a good throw, it wont do any good.
Ok, messing with your response isn’t going to do anything to affect your sleep times. Not sure why this is being suggested.
Unless your throw is so bad that the string is touching an o-ring, changing your response will do nothing. If you are touching a ring on a throw, then we’ve found the very first thing you should be working on! Get your sleeper nice and straight first, and the sleep times will start to come naturally.
If you’re at the point where you’re doing more advanced string tricks, and the rings are slowing you down as you put multiple layers of string in the gap, leave your response alone. Tough it out and learn to keep your string(s) nice and straight in the gap, even with o-rings on both sides. Take a look at the stuff JD does with his Hitman, and remember that you can do it, too. It just takes patience and practice.
When you get more experienced with the HM, an upgrade I would recommend would be to add one red shim to either side. IIRC, this was the only thing JD did to his Hitman in 2003, and you know how that worked out for him. 
you can try to taking out the side caps. Before removal of the caps mine slept for 1minute 30 and after removal 2 minutes.
I really can’t imagine how/why that would work.
I don’t know. It just feels better when I throw it.