Well I woke up this morning, and decided to give it another go.
About the same results as last time.. I relaxed, closed my eyes, and let sleep take me while I comfortably did small contracts. After a few minutes, over the course of a few seconds, something amazing built up "down there", and ran up my spine.
However, as soon as it began, my sphincter got real tight and tingly and once again I was unable to contract. I still have had no involuntary contractions. And the feeling went away before an orgasm was achieved.
I really wish I could experience involuntaries or at least a little taste of the Dry-O/Super-O. Oh well. Just gotta keep at it I guess.