Originally Posted by Marleetet
...The water was backed up all the way to the exhaust/water mixing elbow. Also, when I removed the siphon i heard some gurgling and a slight vacuum sound. The through hull valve for the anti-siphon hose was plug tight enough to not allow me to blow air through it and took some heavy wire to punch through the larvae. ...
Well, that about clinches it, eh?
Not that this hasn't already been a royal pain, but here's hoping you come back with an update -- to the effect you got lucky with no terminal damage!