Okay. Almost every one that emailed me does not have the problem of TechTool's System Analyze feature falsely reporting damage in Mac OS 7.6.1, even with all the additional software installed (as reported last time).
However, Ryan Tanaka noted that Richard Ford (quoted in an article in MacWEEK) warns that canceling an installation of Open Transport can corrupt the System file. This will be fixed in OT 1.2 (the MacWEEK article contains more preview information about Open Transport updates). So, perhaps, some TechTool reports of System damage after installing Open Transport are because the System really is damaged!