Does anyone know if there is a certain technique to separating symbiotes from their hosts, or does it occur randomly?  I am on stage 5 of those optional missions, but it's just crawling along because I can only seem to separate a symbiote from it's host on random occasions and without notification.  It says to just keep hitting them, but I've hit them until they turn into goo even and nothing...  I only need 45 more to finish this off, and if I could do it precisely every time that would make progress go a lot faster.  Thanks!