  In the classical phase retrieval problem in the Paley-Wiener class $PW_L$ for
$L>0$, i.e. to recover $f\in PW_L$ from $|f|$, Akutowicz, Walther, and
Hofstetter independently showed that all such solutions can be obtained by
flipping an arbitrary set of complex zeros across the real line. This operation
is called zero-flipping and we denote by $\mathfrak{F}_a f$ the resulting
function. The operator $\mathfrak{F}_a$ is defined even if $a$ is not a genuine
zero of $f$, that is if we make an error on the location of the zero. Our main
goal is to investigate the effect of $\mathfrak{F}_a$. We show that
$\mathfrak{F}_af$ is no longer bandlimited but is still wide-banded. We then
investigate the effect of $\mathfrak{F}_a$ on the stability of phase retrieval
by estimating the quantity $\inf_{|c|=1}\|cf-\mathfrak{F}_af\|_2$. We show that
this quantity is in general not well-suited to investigate stability, and so we
introduce the quantity $\inf_{|c|=1}\|c\mathfrak{F}_bf-\mathfrak{F}_af\|_2$. We
show that this quantity is dominated by the distance between $a$ and $b$.
