This is based only on my first hand experience after releasing the force known as kundalini..
At first i was using Robert Bruce's methods,trying to reach out and stimulate chakras and regions of the energy body..After some time of everyday work,I finaly learned how to do it,and i was able to move energy at almost every part of my body..
I cracked almost all chakras,but i had problems locating the muladhara,becasue i didn't know it's exact location..
For three days i was trying to locate the area and when i found it,I used my trusty method to rub it again and again,knowing that it's the only major chakra left,and finaly i was touching it..
When it cracked,i felt something like little thunderstrucks hitting my spine from down to up,and after some seconds the whole thing turned to fire.It was burning me big time but in a way that was enjoyable..
Some days after the event,i realize that all mudras were working instantly.I was suprised by the result,because i had tried them in the past but i wasn't able to feel or experience something..
This time i could feel the energy and the power prety clear.So i did almost every known mudra from books and web,activating more regions of my energy body....
This was just the FIRST stage of the kundalini power,because later i found out that this shit goes a lot deeper....
(So my 2 cents about mudras,and why they don't work..)