Never Have Broken Serials
The worst thing about comic rocket is that your comic could be broken.
Let me ask you (from user perspective) why my comic subscription could be broken? Certainly the original comic is not broken, except when their website is down or having technical problem (which is rarely happen).
What puzzles me is why could my serial be broken? Can the serialist just follow from the last recorded page and try to find new page from there?
I suggest you fix the serialist. My idea instead using just two urls, you use three urls as starting comic pages so the serialist could compare the link between from one to two and three to two and store it.