Note: editted in the light of comments below.
A. 3 Thou hast multiplied (H7235) the nation, and not increased the joy: they joy before thee according to the joy in harvest, and as men rejoice when they divide the spoil.
B. 4 For thou hast broken the yoke of his burden, and the staff of his shoulder, the rod of his oppressor, as in the day of Midian. 5 For every battle of the warrior is with confused noise, and garments rolled in blood; but this shall be with burning and fuel of fire.
C. 6 For unto us a child is born,
unto us a son is given:
B’. and the government shall be upon his shoulder: a
nd his name shall be called Wonderful, Counseller, The mighty God, The everlasting Father, The Prince of Peace.
A’. 7 Of the increase (rt H7235) of his government and peace there shall be no end, upon the throne of David, and upon his kingdom, to order it, and to establish it with judgment and with justice from henceforth even for ever. The zeal of the LORD of hosts will perform this.
The word “shoulders” repeats could be B(4), C(5), B'(6), A'(7)
A (3) increased
B (4-5) shoulder
C (6a) child born, son given
B’ (6b) shoulder
A’ (7) increase