The following work was done to the T1-MK2 target in the hotcell between the dates of May 24, 2019 - Jan 30, 2020 (See E-Log #251 for further information):

• May 24: Flushed position 2 with water, purged all positions with air.  Left air running through position 0 over the weekend
• May 27: Switched to position 5, left air running to dry out bellows
• May 28: Started pump out with cold-trap;  Reached "fine test" (TP pressure < 10E-2 Torr) after ~10-15 minutes, left for 2 hours, removed ice build-up then restarted leak detector;  
  Down to 1.0E-3 Torr TP pressure and 1.0E-8 Torr*L/s after ~10min
  Leak checked with 5psi helium, ~0.5s spray: Response at lower delta seal right side (when facing ladder) up to 3.8E-6 Torr*L/s and drift responses from nearby locations
• June 27: Position 1 target removed - no issues, required light tapping with hamme
  Position 4 target removed - lots of hammer hits required
  Both target beam spots photographed.  Saw what looks like hole on Position 4 entrance window (see attached photos)
• July 8: Protect monitor inspected visually using Nikon level by Dave Cameron and Shengli Liu - Nothing abnormal observed
  Electrical check w/ multimeter: all OK
  Observed ground to HV plates while moving ladder from Position 5 to 0 - all OK
  Observed ground to HV plates while moving profile monitor IN then OUT - all OK
  Found intermittent short from HV to ground when shaking the target assembly or tapping the protect monitor cassette:  must replace
• July 18: Cleaned Position 1 and 4 Swagelok sealing surfaces on the target ladder using the Dremel tool with burgandy Scotchbrite
  Ready for new targets to be installed
  Plugs installed at Position 4
• July 24: Target #105 installed at Position 1
  Started leak detector pumpdown with cold trap;  Only pumped down to 4.0E-3 Torr;  Big helium response at lower right delta seal (10E-5 Torr*L/s range)
  Concluded that the leak got worse during the target replacement (likely from the hammering required to remove Position 4 target
  Tightened bolts for lower right delta seal then repeated leak check: same results, therefore must replace seals
  Received replacement protect monitor cassette from Probes Group and installed
• July 29: Probes group did blip test on new protect monitor - all OK
  We repeated the test for shorts with shaking and tapping on the target assembly and monitor - no shorts observed
  Concluded that protect monitor issues is now fixed
• Early Jan 2020: Lower cone and plate removed, ladder removed (old style w/o plate at top)
  Removed seal spacers, the one for the lower right delta seal was stuck, had to use a flat edge screwdriver as a wedge with aluminum hammer to dislodge
  Removed delta seals, observed some deposits or corrosion at lower right seal location
  Cleaned spacers using Scotchbrite on Dremel
  Used 3D printed jigs with glued on burgandy Scotchbrite to clean sealing surfaces (no air ratchet or dremel, polished with manipulators until a clean shiny surface was produced)
  Had to remove bolts for the ladder flanges to clean the surfaces, and when reinstalling one of them it cross threaded and couldnt be removed
  Bolted instead at different hole locations (still at opposite sides of flange) but also had to switch bolt locations on upper seals to do this because bolts will interfere if using same threaded hole
  Eventually got everything back together with new delta seals installed (TBP0454B, machine shop order #44138)
  Note: the upper delta seals were not disturbed - new bolts installed and torqued before old ones were removed
• Jan 22: Leak check, pumped with cold trap: down to 0.0E-10 Torr*L/s and 1.0E-3Torr TP pressure after 9.5 minutes
  Using 5 psi helium, 0.5s spray;  No response at any previous locations;  Very small drift response up to 0.5E-10 Torr*L/s
  Concluded that leak is fixed
• Jan 26: Base plate and cone reinstalled - no issues
• Jan 30: David Kyle and Shengli Liu re-tested the profile monitor and protect monitors - No issues
  Measured vertical and horizontal positions for all targets and protect monitor, updated measurements sheet (PDF attached)
  Ladder moved to Position 0
  Target assembly ready to be moved to storage pit