You will find that Hose And Soft Axle pieces will have permanent curves and bends. Buying Used ones on Bricklink will probably have a bend to it. Nothing wrong with that unless you want one that is straight.
What you are building you might want it curved but sometimes these pieces are bent in ways that they are probably unseeable. I have started an experiment on how to get these straight.
For both types of pieces I used Technic bricks. This one is for the Soft Axles.
This one is for this type of Ribbed Hose. Both fit in the holes of the Technic bricks. As you see, I have a lot that are bent. This type of Ribbed Hose seems like it is going to straighten faster than the Soft Axle. The Soft Axle is going to take a long time. I slid them all in yesterday. I will update this page when I am done with this experiment.
UPDATE: The Ribbed Hose after 14 days are now fairly straight. The ribs make the piece more flexible. The Soft Axle aren’t even close yet.
UPDATE 2: Over a month on the Soft Axles and most are very straight. There are two different materials where one is more rigid than the other. These are useable now. Longer would make them even better.