Open a Device Card, select the Spares section and click Add
Use the + to add the parts as need - You can filter / search for parts as needed
In this case I selected a belt which was then added the spares
Spares will also be added to a device when used in a task (any type of task) for example, I have a task to replace a bearing, I go to the Used spares on the card and I see only the one added above
I search for the part I will use, and select it, now it's added to the task and selected as used. This means the cost of repair includes this part, and the stock level will be adjusted. Note you can setup which stock is used read here
It also means this bearing used is included in the Spares section of this device, and next time I can easily select immediately, saving time.
NOTE: You can copy a Location with devices or an individual device. When copying a device all the spare parts that have been added to the device are also copied.
At present you cannot add spares to a device via import or other mass update methods, this is something planned for the future.