I used to have the same mower, a green STX 38. I think the hose is an overflow hose, nothing special, or a breather hose.....I forget. I sold mine for $150 and it was in good running condition. If her deck is a black deck, it isn't worth keeping the mower going, if it is a yellow deck, then it is maybe worth fixing if it is economical to do so--kind of depends on its current condition. However, before fixing, have you thought of finding her an older cub cadet and have her mow your yard?
The rebuild kit could be pricey. I had to have mine rebuilt when I first got it and it was only 2 years old. I got rid of my green machine when I realized that their
green was costing me my
green because they thought their machines were made of
gold. I would look for a good used cub for her for a couple of Franks...
Now, about that gasoline... I am very careful to do my best never to get gasoline on me. MTBE is added to gasoline to comply to the clean air act and it has a high level of toxicity. Although most states have banned it and the government plans to phase it out, I still am very careful whenever I handle it. I've used isopropyl alcohol and lemon juice on my hands whenever I did get some gasoline on my hands. Once, when I was out of lemon juice I did use pickle juice and it did alright......Side effects, your hands smell like a sandwich.
Cub Cadet 123