Problem(s) Encountered:

MIS guider probe CCW limit switch is not stopping the probe motor when it reaches (x,y) = (0,0).  The probe motor runs continuously and audibly. This problem only seems to occur when using 'Preset --> Origin' in xmis2 (a process that also seems to be activated on xmis2 initialization, e.g. during the restart process from lightning shutdown). On returning the probe to (0,0), the message 'Warning - not at Y CCW limit' appears in the xmis2 window. Spoke with Eric G, it sounds like the Y limit sensor might be faulty. 

Solution:

As a workaround: If the guide probe motor is audibly running continuously, hit 'stop' in xmis2. To return the probe to the origin, command it to (x,y) = (0,0) in xmis2 rather than using 'Preset -->Origin.’  Until the Y limit sensor can be fixed, we were advised not to shut down the MIS as part of the lightning shutdown procedure.

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Lost the y-stage ‘0’ limit switch (see image below).  This was a relatively new switch so I’m a little frustrated to have had it fail again.  At least this time, unlike last, the drive belt is still in one piece.  Switch has been replaced.  I also replaced the bolts holding the switch in.  The new bolts have broader heads.  I’m hoping this will distribute forces more effectively and thusly increase the life of the switch.