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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.
