Following Roice's instructions for solving the 3x3x3x3 I experienced that n=
ot only the 3 color pieces can return to their home place with one color at=
the right place and the two others flipped (the piece is mirrored) but ALS=
O the 4 color pieces. This time one color is okay and the three others are =
exchanged in a 3 cycle. To get rid of this situation the cross color sequen=
ce from Roice ( =3D second 4 color sequence) is not sufficient. Let be 4c1 =
and 4c2 the two 4 color sequences of Roice. With two properly placed 4c1 yo=
u can produce a 3 color cycle for one 4 color piece disturbing two other 4 =
color pieces. At the end I needed a three color cycle for two pieces with a=
ll other pieces in place and correctly oriented. Here a commutator of my 3 =
color cycle and 4c1 of Roice did the job.
Placing the 29th edge piece is the most difficult part of the solving proce=
dure if you are unlucky and get a flip. You have to arrange an excursion of=
the flipped piece exactly on the last free edge pieces.