The manual for the Singer 15 should work for most or all functions of your Hoover. It's a clone of that model probably from Japan and probably sold under more than one name.
Some of the Japanese clones are actually smoother and quieter than the Singers they copied.
How lovely to have this machine back and a little bit of your mother close. And mercy, I just noticed that it's only been a week since she passed - you must be a lost soul right about now. I'm so sorry for your loss - I will light a candle at mass, tonight and keep you in my prayers.