I did a complete search of my computer for Legendary_707.isd and also went through the files one by one, but did not find it on my computer.  Could that be the problem?

Thanks, I'll look for the file later today.  I wonder why it didn't show up during a file search using the exact name of the file?

Also, I'm smacking my forehead thinking I am an idiot.  Last night I set up for a flight, keyed in latitude present position, pressed Insert once (as reported to you earlier, the key remained lit), keyed W and the CDU accepted the longitude input, exactly as you wrote.
I believe my confusion was thinking the Insert key light should go out every time it is pushed, and I had that impresssion from the manuals.  Before my first use of the INS I read the UserManual and it describes the Insert button this way (Quote):
"11 INSERT key
It is lit while data is being set by the CDU keyboard and goes out when pushed to insert it or CLEAR is pressed to abort current input."

Then I read the Tutorial, and for setting present position it says, "Our ramp position is:N42°21.8 W71°00.3. We will type, on each of the
installed INS units: N, 4, 2, 2, 1, 8, INSERT, W, 7, 1, 0, 0, 3, INSERT"

I understood from those 2 statements that the insert light should go out each time the insert button is pushed, which it does for waypoint insertion, but now I understand  what you meant when you wrote that present position is different.
I won't bother you any more about this.  I'm going to log several flights with the INS installation just as it is now to be sure i've got it, and then I'll try to reinstall the ADEU.  Thanks for all your help.