Hi Dave
I had a similar problem with my sprockets after I rounded off the tops of the teeth.I came to the conclusion that I had removed the pitch angle off the sprocket causing the track to jump.I bought a second hand pair of sprockets with the edges of the teeth were not filed off.The same thing happened,tracks jumping and snatching.Then the penny dropped I had the track pins chromium plated just before the problem appeared.Further investigation of the track found several links binding with there neighbours thus causing the link to bind on the sprocket.Once all the track was freed up I had no more trouble,and I did not need to buy a second pair of sprockets.As they say you live and learn!
All the best Jeff Hyder.