When the twist release quit working, I took a cold chisel and split the ring which was hard plastic. With the ring removed there was a spring loaded pin under the ring. I can only surmise the ring,when turned, depressed the pin to release the PTO. I used the spring loaded pin to release the shaft about 10 times (it was very diffcult to press down with my thumb)before it stuck, that is when I pulled the spring off the pin and the pin fell out. Still would not release.