Graphite crucible lifetime

Folks, I’m a newbie with casting and would welcome some advice and

When should I replace my graphite crucible in my electric melter? I
melt bronze in an electric crucible furnace that takes a 90 ozt Rio
graphite crucible. The crucible is slowly pitting and deteriorating
and wearing out. The walls are getting thinner, but I don’t know when
they will be ‘too’ thin?

What happens when these crucibles fail? Do failed crucibles destroy

What is the risk? My casts are usually between 100 and 200 grams of
bronze. Because I am melting bronze I bought a custom crucible
furnace to get me to 1250 C if needed. This furnace is similar to the
Electro-Melt or other automatic melting furnaces.

Do you have experience or stories you can share? Thanks tremendously
for your advice.