How does Rogozhin's (2, 18) universal turing machine work?
I see (at least) two errors:

The head position should be at the beginning of $S$; and there is an extra 1 at each $P_i, i &gt; 1$: $P_i = bb 1^{N_{i_{m_i}}}1b....b1^{N_{i_2}}1b1^{N_{i_1}}$

c⃖₁ c⃖₁ b  b  1  1  b  1  b b &gt;1  c  1  c  1  c
                 ^            ^
                !!!          !!!


Don't forget that the rest of the tape should be fille with $1^{\leftarrow}$ (the balnk symbol).

A few years ago I also examined its behaviour; you can find the javascript version I made here: click "Small" to load it, then fill the tape (click on the second gray row to place the head), and click "Step". You can compare it with your implementation.