With Fabian and Hirata-san.

Today:

• We zeroed the BS TILT OL.
• We removed the tank lid and inspected the blades. We did not lock the IP during the inspection so as to minimize any perturbation to the alignment. However Hirata-san worried that he might have bumped the IP slightly while removing the lid.
• All three of us inspected all of the blades with lights, and there were assorted fine scratches, but we did not see any of the characteristic X-shaped stress fractures that were so obvious in the SR blades yesterday.
• We replaced the tank lid.

As a result of the inspection, we are comfortable using the existing BS top filter blades.