I've moved PR3 back to latter half of O4 based on the slider, not OSEM.

Assuming that the ITMX angle is good and the beam deflection angle through the BS is the same as before, the plan to get ready for the arm peeking is as follows.

Find a good IM4 angle where the ITMX reflection comes back to ISCT1 camera (Louis is working on it).

Once that's found, align PRM, refine PRM and IM4 alignment to have a good PRX flash.

After that we might have to walk the beam on PR2 without touching ITMX and PR3. Unless there's a convenient script to do that, you'll move IM4 a bit, change PR2 so that ITMX retro reflects, and change PRM to recover PRX.

By iterating, you'll eventually settle on the beam position on PR2 that will give you an ok signal on LSC or ASC (hopefully both) POP sensors in HAM1. 

Also work on the ISCT1 alignment for the ALS beam, but this will be on Monday.