that is a nasty situation all around
the stack is filling up with lime.....
it is probably best if to change out the
entire stack if possible ...while you are in combat already.
if not you can try to get someone to rheem out
that line with a large cutter... maybe work??
or it will break it up jsut enough to stop up the line further..
you can pour pure vinegar down the line and maybe it
will eventually break it down.... although that could take forever.
muratic acid will eat through it too ....very quickly
but its a very nasty smelley thing to mess with...
I have gone the Muratic Acid route before.
just change out as much of the stack as you can
while you got the chance to do it...