Seat back adjuster knob broke off ..help?

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Today I lowered my seat back with that knob located on the lower right side of the seat back and it broke off. Now I can't get the seat back up to a good driving position. Actually the alluminum part that is mounted on the seat and and holds the knob is what broke off at the base. I now have the plastic knob with half the alluminum part. I can see a nut now where the alluminum part was attached. I was thinking of taking off one of the parts from the rear seats but need some advice on how to remove it properly. Can anyone help?