"Further, The Clark Concise A-S Dict. has: -clýsan v. be-c. [clûse] [[under "clûs"]]."

I had a look at Clark, and it's not clear to me what the material in the square brackets is supposed to be. The introduction makes no mention of what these brackets are for. It is not obvious to me that is is an alternate form. Other entries suggest that the square brackets are for etymologies or modern reflexes.

http://www.gutenberg.org/files/31543/31543-h/main.html

"Most of it is likely right but it would be nuts to say that it's all 100% right."

I never said anything was 100% accurate. I just said that there were some things we could be reasonably certain about, and that if you have a different hypothesis, you need good evidence.

"first we hav that the Saxons didn't mark their vowels … Or maybe I should say that they seldom did."

Are you talking about how OE writing doesn't distinguish long and short vowels? You're right, but the comparative method, as well as examination of OE prosody, and examination of the modern reflexes of OE words, let us determine the values of the vowels.

"The ū often, but not always, yields 'oo' in today's English. It seemingly did yield 'oo' in some of the ME spellings of close (cloos)."

Except that as I've already said more than once, ME "oo" was not prounced /ū/. It was probably pronounced something closer to /o/. It can't have been pronounced /ū/ in ME, because words spelled with "oo" became to be pronounced /ū/ after the Great Vowel Shift. And OE ū usually became modern /aw/ as in "house".

"Yes many, gewiss not all, of the ȳ words today is spoken with a long ī. However, that IN NO WAY means that it was said that way in OE."

I never said it was pronounced with a long "i" in OE. I said that if "clysan" had survived into modern English, it would probably be pronounced with a long "i" now.

"However, they did adopt the French spelling and either thru the GVS or with pronunciation chasing spelling, the pronunciation shifted more to the 'o' sound as well."

The Great Vowel Shift would have had nothing to do with long /ū/ or long /ȳ/ turning into /o/.

"In Clark's Concise Dict. we hav fyrhto, fyrhtu (fryht-, N) f. 'fright,' fear, dread, trembling [forht] … whoa … fyrht = forht? yep … y=o …"

Is "forcht" even Old English? Anyway that's a short /y/ in "fyrhto", and we're talking about long /ȳ/.

You gave some examples of "u" alternating with "o" at the end of a word in OE. That's a specific environment, and it doesn't necessarily mean that they alternate in other environments. And these examples concern short /u/, not long /ū/.

"So you see, it isn't a great leap from OE clȳs-/clūs- to close."

You havent provided any evidence that OE "ȳ" was pronounced /ū/. And you've provided some speculation, but no evidence, that "close" was a French respelling of the OE word because the vowels were similar.

"And we often see pronunciation chasing spelling (route is more often said as 'rowt' than root; thou was once thu rather than "thow"

I'll give you "route", the pronuncation with /aw/ is a spelling pronunciation. It happens sometimes. But the pronunciation of "thou" didn't change because of the spelling! It changed because of the Great Vowel Shift.

If you believe that "close" is the result of a respelling by someone not familiar with English, then my question is: why did it stick? Most French respellings were just that: changes to spelling, not pronunciation. For instance hus - house, mys - mice, scame - shame, gylt - guilt. Why did this respelling of "y" to "o" stick, and change the pronunciation? Why did this not happen with any other words? What other letters should we expect to see respelled?

Simply saying that it was really chaotic and we can't be sure of anything is not an answer. Historical linguistics has a methodology for finding things out, and it's been really successful at showing that sounds don't change randomly, but that there is a regularity to sound change.

No, I'm wrong. Many spelling conventions were introduced by French scribes not fluent in English (A Biography of the English Language by CM Millward, p. 137). But that still doesn't mean we don't need evidence for our claims.

"We all know that Old English into Middle English was, after the conquest, ascribed spelling and lettering variants by non-English speakers"

We know nothing of the sort. Estimates on how many Norman French speakers lived in England range from 2 to 10 percent of the total population. Most people in England had no direct contact with the Norman French-speaking nobility. Yes, many words were respelled, but not by non-English speakers.

If you don't take me seriously, then I suppose you don't take historical linguistics or the comparative method seriously. I guess things are more fun when you do away with all those pesky rules.

Gallitrot:
AnWulf thinks the change from "clȳsan" to "close" was merely a spelling change. The sounds /yː/ and /o/ are so similar that people simply respelled the word with the letter "o".

Which dialect did this happen in? What exactly does "similar" mean? Exactly which vowels would be likely to be respelled? Why don't we see this process with other words? Usually, spelling follows pronunciation, not the other way around.

In fact, why can't I use this argument to just say that any modern word is the reflex of an OE word, if the sounds are "similar" enough?

The only evidence AnWulf gives is a quote by Trevisa where the word is spelled "cloos". But in ME, "oo" was probably pronounced like the modern /o/ of "home".

It's certainly fine to speculate when the etymology is unknown. But the etymology of "close" is well understood. If you think you have a better account of its etymology, then you need good evidence.

No, I am not agreeing with AnWulf. There are well-understood sound changes in the history of English. The change that AnWulf proposes is not one of them.

The point is that it's not complete chaos where any guess is as good as another, as AnWulf suggests. We know what the sound and spelling changes were and we can explain them.

It's possible there is "custy" from OE cystig. There certainly are examples of OE "y" becoming something other than Modern "i". Some West Saxon words respelled "y" with "u": crycc - crutch, dystig - dusty. Some Kentish words respelled "y" with "e" as in cnyll - knell. I recommend The History of English Spelling by Upward and Davidson as a good overview of the topic.