This is quite an engaging documentary that introduces us to four specialist technicians who maintain some of the musical instruments that are provided free to pupils in the Los Angeles school system. Prefaced by a few words from each of the children who benefit from the violins, tubas, pianos and saxophones to name but a few, we then meet four of the people - from a variety of interesting, sometimes quite traumatic, backgrounds - as they show us just how meticulously they work to keep these instruments alive and useful. To be honest, I could have been doing with just a little more performance ...