*2 chords: 1W & 3W interchange (M: 1,2,3; W: 3,2,1)*

1–
: All set | Circle6 &frac12; way L ;
  1c followed by 2c+3c cast cclw (M up, W down) to invert set |
  all cross LH to original pl
9–
: 1c+2c cross RH on diag **while** 3c set | 3c+1c cross LH **while** 2c set ;
  2c+3c cross RH **while** 1c set | 1c+2c cross LH on diag **while** 3c set
  (Mside: 3M,1W,2W; Wside: 2M,1M,3W)
17–
: All cross RH | 2c followed by 1c+3c cast cclw to invert set ;
  Circle6 &frac12; way R | all set (in same places as [16])
25–
: 1W+3M+2M & 1M+2W+3W RHA{3}, 1c lead LSh Snakes{2} to change ends, LHA{3} in same groups.  
  In the last bar(s) of the LHA 1c dance out ends & cast to 2pl,
  2W & 3M (2nd in Snake) end in 1pl/3pl own sides,
  2M & 3W (last in Snake) pass LSh to other end (M: 3,1,2; W: 2,1,3)  
: *NB the instructions are not clear about the final progression or how it is achieved.*
  *The above is a working interpretation.*