Hello Bunny and all.
As an adult student of the Russian language,
I'm finding that there are certain sounds that I
struggle over because I was nervous about pronouncing
them incorrectly in the first place.
Unfortunately, it has become a stumbling block,
not that the couple of sounds are hard to pronounce,
but that I have a 'mental block' with them while learning
vocabulary, trying to pronounce things.
So, I think you are absolutely right. Take the time to
correct pronounciation. Make *sure* that they have
that right, or at least that they are confident that
they are pronouncing properly (and you're
confident that they're doing it good enough).
It's an annoying thing to have this 'mental block' over
a couple of letters. It's getting easier, but
it still snags me sometimes.