Hi John and Happy Holidays!
I think Johns suggestions were good ones. If all of that checked out ok and you still feel that the train is binding then it’s possible that you have a depthing problem between one or more of the wheels and arbors. This can happen if a hole in a bushing that you inserted is offset from it’s original location. Also check to see if there is enough clearance between the pivot and hole. A small amount of side shake (and end shake) is important. Something you may also want to check is that the pulley at the top of the case is turning freely when the strain of the weight is applied and that nothing is obstructing the line and or the fall of the weight. Also…you mentioned that the volume of the ticking increases and decreases. Does it alternate between loud and soft a few times before it comes to a stop? If so is the number of ticks between the high and low tick volume consistent or is it random? If it is repeating how many ticks would you say there are between the two levels?