ZB3,

If you search on "tube collar" in this forum, you will see a few discussions of this operation. Here is one:

http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=2;t=004346#000000

I think you will have to loosen the collar a little in order to slide the "ball/bell" backwards (the collar tightens the seal against the tube). Also, the ball/bell/collar will not slide backwards unless the tube is completely cleaned.


Tim