I stumbled across where to get 7.5.1 (also written as 7.5 Update 1)
Visit http://www.hpe.com/support/softwaredepot
Ignore the link at the bottom of the page under "Other useful links" named "Systems Insight Manager product information"
Expand Product Category -> "Insight Management" -> click on "Insight Control". That takes you to this page: https://h20392.www2.hpe.com/portal/swdepot/displayProductsList.do?category=INSIGHT
Click on "HP Insight Management Media"
Review the notes on this page and then click the green "Select" button on the upper right.
Log into your HP Passport account.
Proceed through the process of downloading the ISO file. As of this writing the file is named "Insight_Management_v7.5_update_1_May_2016_Z7550-01909.iso"