In any self-respecting schematic, where the component is, there should be a reference next to or near the part in question. This may include a unique identifier for the part in that circuit and should also mention the component number. For example, an MCU may have IC2 as a unique identifier (the 2nd IC chip on the board) and PIC18F2680 (the part number of a micro made by Microhip).

It may be helpful to post a link to the notes or the part number. Context can be a wonderful thing.

Are you aiming for contact or non-contact? Are you interested if power is getting to the socket or if the switch is on and power is getting out? Do you want detect voltage presence or current flow?

@IgnacioVazquez-Abrams Also a good point. Though I doubt they would put as low a value as 66 Ohms for the pull-up. Added for completeness. :)

Apologies. I thought I read somewhere that they were 5 V tolerant. Maybe I misread... or maybe that was the device I was using. I'll update. Thanks. :)

Use an ESD safe brush if you want to clean components. While it may seem trivial, you don't want to spend all the time cleaning the board only to find that it doesn't work because you damaged a chip. The brushes are pretty cheap and can be bought from pretty much any tech store. Most dust will build up on the top side of horizontally orientated boards and wherever there is a fan. Most GPU and CPU heat sinks can be removed to clean. Just be careful of the thermal paste.

Good point. I failed to mention that. Will update now.

@JYelton Probably the same assignment... ;)