The six tabbed forms were massive, many with several tabbed subforms, filling 1920x1200 screens with very little white space.  So, yes the 6 forms were much denser than what normal folks use and could cause memory problems, I decided.
Compacting and repairing, almost daily, kept the database healthy for over 6 years.  When I got the "you don't have exclusive access..." errors, I split the database as Alex Hadley recommended.  That error went away (Thanks, Alex, I was hero for a bit) but users started having memory issues with their computers.  Desperate to find a solution, I found a couple other folks griping that they did not have the "exclusive access" errors until they migrated to Access 2010.  I realized that I had just dumped my whole database into a blank 2010 dB, hoping to get newer features. I started rebuilding tables from scratch but gave that up when I realized the AutoNumber IDs would be renumbered if I pasted data into my new tables.  During the last weekend, I recombined the dB as Richard Rost taught me. Then, I cleaned out an old 2012 backup (old enough to be sure I was in Access 2007) and imported each group of objects into that old, 2007 version.  The unsplit database ran healthy and fine all week. And, with the single dB, we are able to continue taking the dB with us on trips to customers (tribes) at remote sites in Alaska and have all of their records on the small 90MB file.  
I think there is bad ju-ju in Access 2010.  I am happy now.  Lots of that happiness is thanks to Richard's lessons.  His lesson on importing was much faster than copying and pasting groups of objects.

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Reply from Alex Hedley:

It's a shame that didn't work, glad you managed to restore from an backup.