Move VERT and HORZ stage motors to reposition the low-Z sample box until the bellows is not bent vertically or horizontally. VERT is about 42, and HORZ is about 25, but check by eye and adjust if still bent.
Look behind the back of the low-Z sample box. There is a rail along the back of the box attached to the stage plate. There are two allen hex bolts going through this rail to hold the back of the low-Z box to the rail. Use a 5/32" Allen wrench to loosen each bolt a few turns. This will allow the box to slide upstream and downstream on the stage.
Remove the clamp for the O-ring between the two gas sections.
Slide the Low-Z sample box downstream to separate the two gas sections. Remove the O-ring and old polypropylene film. You may see a small cut in the polypropylene film where the beam burned through.
Roll out and tear off a new piece of polypropylene film from the box of SPEX 3520 Polypropylene. About 3" of length is enough. Do NOT touch the center of the film, only the edges - finger oil has Sulfur in it!
With one hand, lay the film flat against the flange to cover the hole in the front end / I0 gas section. Then push the O-ring against the film with the other hand.
Slide the low-Z box back upstream to seat the O-ring. Then clamp the flange / O-ring / film assembly using the clamp.
Test that the two gas sections are separated again. To do this, check that the He flowmeter is at a high value (it reads H +F above 500) and decreasing. The initial high value is because there is heavier gas (air) being purged out of the Front end / I0 section. It should eventually settle around 200-240. If the flowmeter value is already lower than this, this means there is a hole in the film. This often happens because the O-ring can cut the film. No worries! Just unclamp the assembly, replace the film, clamp and test again!
Once the separation of the two sections is confirmed, retighten the two allen hex bolts in the back of the low-Z box using the 5/32" Allen wrench. This ensures that the box moves properly with the stage when you move the HORZ motor. If it is kept loose, the bellows will tend to oppose this HORZ motion and make scans with the HORZ motor not reproducible.
That's it! Make sure the flowmeter settles back down to 200-240 and wait 5 to 10 more minutes to ensure no air is in the front end. Then you can turn on the X-rays and continue!