To repair the plastic fuel lines (at the secondary filter), if you leave the ends of the barbs covered with the old plastic tube you can use 5/16 i.d. fuel hose with clamps for new lines. I wonder if you could similarly clamp a short length of fuel hose to the barb here (leaving it covered with the old plastic) and just stuff the end of the plastic tube into it - would it seal - like the vacuum lines do?