I explained how to use a laying tool in my Using a Laying Tool post.
In this post, I will explain how I use a needle trolley thread controller.
I'm left handed so I take my threaded needle in my left hand, needle trolley is on my third finger - works best for me. I make the first leg of the stitch.
I release the needle to the underside of my fabric, right hand takes and holds the needle. I insert the trolley into the thread before the stitch is completed. I rock the thread up...
then down at the same time pulling on my needle from the back of the fabric. I want the threads to lay nice and even.
Once the threads are pulled from the back and the stitch looks good, is even and complete...
I remove the needle trolley from underneath the threads.
I repeat the process for the second leg of the stitch.