strings -- buzzing, ringing

[Charles Neuman]

I'd really like to hear people's techniques for fixing buzzing or ringing
problems in strings. (My string problem seems to be solved, but I'm
interested in the topic in general.)

Some questions:

At what point do you start sanding the v-bar?
Under what circumstances would you change the pressure bar height?
At what point do you decide to replace the string?
Have you encountered string problems that you can't fix?
Does hammer voicing ever help?
Do you recommend any specific techniques?

It seems like string problems could be real head-scratchers, and I'm sure
there are various approaches. Any ideas you wish to share would be very
interesting to me.

Thanks,

Charles Neuman