Watched your video, doesn’t look good for the tube…
If anything is out, it’s because you changed the whole geometry if you squared it up…
That brings into question are you proficient in alignments and how well did the alignment go?
Did you check the tube output before m1 to see what the beam looks like?
It should be in TEM00 mode or resonance. If not that a problem as it will never properly align…
Probably answer some of your question if you follow this thread…
If you have questions sing out… we’ve all been there … 
Good luck
