Tom, you asked, "Please name me a single instance of where or when one of the "dead guys" (Pre-WW2) did any "renovating" of existing courses---either their own or another architect's... almost without excpetion they were not doing "renovation", they were doing their own "redesigning" of the courses of other architects."
Renovating or redesigning, you are looking at what I stated semantically rather than with the idea that whatever was behind the new work, it wasn't with an idea to preserve, but to either change &/or improve, therefor they usually didn't "research" the earlier work.
Oh yes, Tilly did do a great deal of renovating on courses he was not redesigning. A good example can be found on the recent thread about the Wee Burn CC. After a complete examination of the entire course, he recommended changes to 3 holes only. He recommended leaving the rest of the course as originally designed. That, my friend is a renovation and not a redesign. The year was 1936.
They are in the process of restoring the course and are researching both the original design and the Tillinghast work on those three holes so as to preserve both.