Embalmer, unless your sprag is severely worn I would put money on the torque limiter being the problem. As a reference point,
HERE is a ducati sprag that was unable to start the engine. You will notice that the spring that holds the sprag together is completely destroyed. You can also see that there is severe wear on the inner race(the sleeve on the drive sprocket). If yours isn't as bad as that one then I will guarantee that the torque limiter is the culprit.
Don't do what I did and put it together with all new parts only to find that there was nothing wrong with your original sprag.
Unfortunately you will have to put it all back together to test the torque limiter.