OK problem is, my dad in-law has a mobile home and neither of the toilets will flush out. He recently bought it and had it moved hence this is when the problem started. The toilets have not flushed out since day 1. Everything else seems to run out OK, shower sinks etc... Could this be a venting problem? Laymen terms as I am new to plumbing haha. I learn as I go from AMHD!!