Y. Aso, Y. Fujii

= As reported in klog#6323, klog#6335, either SF/BF/IM is rubbing somewhere with high possibility. =
- check points would be at SF-GAS for PR3, BF-GAS for PR2
- Here we did a test with PR3: we changed the SF-keystone height by SF-FR since the SF-keystone did not oscillate much. Then we found following stuffs:
  -- when we changed the SF-keystone height by SF-FR, we found 
    --- SF-GAS shifted only a few um (thish means the keystone height was not shifted much and this seemed to be because the primary coil is out of linear range.)
    --- Not only SF-GAS, BF-V, but also BF-GAS were shifted as well. (If everything is suspended properly, (dc position of) BF-GAS should not be changed by SF-FR operation.)
based on this, we started to suspect that IM might be sitting on the earth quake stop, this is not 100% sure though.

- In addition to (except for) this issue, BF-GAS is oscillating at around 200Hz somehow (might be related with aliasing) and this seemed to have keystone-height dependence.
- PR2 also had these 2 problemsas well.

- We will try to change the keystone height by FR again and if we fail to make the change (with high possibility yes), we will open the chambers, starting from side chambers to top. 
The details will be posted in the coming week.