Edward Hills shows some interesting points.
But are they conclusive or just opinions?

Quote:
In the Epistle to the Hebrews there are three Old Testament quotations which have been the subject of much discussion. The first of these is Heb. 1:6, And let all the angels of God worship Him. This clause is found in Manuscript B of the Septuagint as an addition to Deut. 32:43. On this basis the author of the Epistle to the Hebrews has often been accused of citing as Scripture a verse not found in the Hebrew Bible. The text of the Septuagint, however, is not certain at this point. Manuscript A reads, And let all the angels of God give them (Him) strength, and this is the reading adopted by Rahlfs (1935), one of the most recent editors of the Septuagint. If the reading of A is correct, then the text of B must have been changed at this point to agree with Heb. 1:6, and the author of the Epistle to the Hebrews could not be quoting it. He may have had Deut. 32:43 in mind, but the passage which he was actually citing was Psalm 97:7, which is found both in the Hebrew Old Testament and in the Septuagint and which reads (in the Septuagint), worship Him all ye His angels.

This one sounds inconclusive,to say the least.

Quote:

The second Old Testament quotation causing difficulty is Heb. 10:5, Sacrifice and offering Thou wouldest not, but a body hast Thou prepared Me. This is a quotation from Psalm 40:6 and is found in this form in the majority of the manuscripts of the Septuagint. The Hebrew text, however, reads Mine ears hast Thou opened instead of but a body hast Thou prepared Me. Because of this the author of the Epistle to the Hebrews has been accused also of using a mistranslation of the Hebrew text as a support for the Christian doctrine of Christ's atoning death. But this is not a necessary conclusion. For in Psalm 40 and in Heb. 10 the emphasis is not so much on the sacrifice of Christ's body as on Christ's willing obedience which made the sacrifice of His body effective. Because of this emphasis the inspired author of Hebrews was justified in regarding the Septuagint as sufficiently accurate to express this central meaning of the passage. The opening of Christ's ears to make Him an obedient servant he considered to be the first step in the preparation of Christ's body for His obedient sacrifice.

Don't know what he was driving at there.

The third Old Testament quotation to present a problem is Heb. 11:21. By faith Jacob, when he was a dying, blessed both the sons of Joseph; and worshiped, leaning upon the top of his staff. This is usually thought to be a reference to Gen. 47:31, where the Hebrew text and the Septuagint differ, the former stating that Jacob bowed himself upon the bed's head, the latter that he bowed himself on the top of his staff. This difference is attributable to the fact that in Hebrew the words bed and staff are the same except for their vowel points, so that bed could easily be mistaken for staff and vice versa. It is usually said that Heb. 11:21 follows the Septuagint reading of Gen. 47:31, but this too is not a necessary conclusion, since actually Heb. 11:21 refers not to Gen. 47:31 but to Gen. 48:1-22. Here Jacob sat apparently, on the edge of his bed and may very well have had a staff in his hand.[/quote]
No concise victory of the LXX here either.
HMMM.

Holy Bible
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