solace67,
I'm not sure about the .46, but I have a TH .61 and they use a pinch test for both the low and high end settings. Are you setting the low end or high end? The engine response you're looking for is different for each. TH engines are a little more complicated to break-in and the instructions definitely leave a lot to be desired. Once broken in, however, they are very reliable. If you can, have an experienced modeler give you a hand. Just remember to be patient and give the engine time to accept the new needle settings.
Good luck
Rufcut