Head odors/boat stinks. Venting from holding tank appears to be the 2" port line that would also serve as overboard discharge if obd option was installed. There may be another vent on starboard side but I cannot find one. Toilet is a Jabsco Electric Conversion. Cannot determine if there is a vented loop from bowl to holding tank. Tank is right at or partially below waterline. Bowl is above waterline. Any 3260 owners out there who can tell me how their system is plumbed/configured?