I had a tube break this morning. I installed my spare backup tube and there seems to be something wonky. I am pretty sure the old tube produced a fairly solid beam of about 3/8" to 1/2", The new one does the same size, kind of. But its only the outline of the beam also by the time the beam or outside of the beam makes it to the third mirror is grown in size and lost intensity.
In the picture below you can see the output from the tube approx at mirror 1. You can see its plainly not a dot but a ring??!?
What do you think?