I have a three weight Vienna with the quarter striking train "skipping". What I mean is that it will repeat the count 1,2,3 or 4 many times over before it stops and triggers the count train. So, after a day or two the right weight will be very low or on the bottom of the case. I have removed the face and watched this skip, tried adjusting the tension on the rack but the skip always returns. What might the problem be?