User blog comment:LittlePeng9/Random Turing machines/@comment-5150073-20130410080930/@comment-1605058-20130410120751

Each case can be repaired with exactly 1 state. We have to replace 1 1 _ r 2 with 1 1 _ r 21 and add these transitions:

0 _ _ r 19

10 1 1 l 20

19 1 _ r 19

19 _ 1 r halt

20 * * l 20

20 x _ r halt

21 1 1 r 2

21 _ x r 3

I'll quickly repair both power and root machines