The Collaborative International Dictionary of English v.0.48:

Shamble \Sham"ble\, v. i. [imp. & p. p. Shambled; p. pr. & vb.
   n. Shambling.] [Cf. OD. schampelen to slip, schampen to
   slip away, escape. Cf. Scamble, Scamper.]
   To walk awkwardly and unsteadily, as if the knees were weak;
   to shuffle along.
   [1913 Webster]