The best solution is to use one of those miniaturization rays on your guest and send him down to fix the clog.
If that is known to be the problem, then another option is to use something like this w/ the spring end unwound to make a hook to try and snag the obstruction and pull it back.
If that doesn't work, the the disgusting option of disassembling a failed Vacuflush system is probably the only option. At that point replacing the hoses w/ new might as well be performed. Mine takes two 10' sections, w/ a coupling and hose clamps at the joint. My boat has an access panel to permit proper assembly / disassembly.
http://www.ebay.com/itm/Drain-Cleaner-1-4-inch-x-25-ft-Portable-Sewer-Snake-Clog-Cable-Auger-Plumbing-/251705178750?epid=1700152805&hash=item3a9acc3a7e:g:kp0AAOSwX61ZCmbS