Thanks. Interesting. Even though I had "instant email notification" checked for this thread, no email. Hmmm. In any case, I did search before I asked, found plenty of "links" to older versions, but they all point to the same download page, which only has a link to the most resent version, hence my post here AFTER searching. So, checking again, I found buried in a thread what I assume is the explanation you refer to. So, for the benefit of anyone else searching the same info by the keywords "older versions"...
1. Go to the standard Teensyduino download page.
2. Right click the download link for your OS, and "Copy Link Location" (or your OS/Browser's equivalent...)
3. Paste that into the url string of your browser, DON'T HIT ENTER YET.
4. Change the "td_xxx folder in the url to the version you seek.
5. Hit ENTER & download
Note: The above should work until such time as the website folder naming structure/old version policy changes.
RE: my problem, I need to work out some I2C issues to the best of my ability before I bother anyone else. If I hit a brick wall, rest assured I'll ask for some help

I appreciate the offer.