The lower hose with the spring in it is the most notorious for collapsing. It rusts or deteriorates over time or if it is out of position (not stretched end to end) it will leave room in the hose for it to collapse.
I didn't even think they made the spring supported lower hoses anymore and went to ribbed style.
I'm not putting all my money on the hose as a problem, I just want to eliminate it as a potential problem.
