You need a pocket size Dmm, nothing fancy and the smaller the better! I have a old Beckman DM78 I carry with me all the time and it's perfect for mechanical/electric troubleshooting
http://kuzyatech.com/vintage-twins-b...and-hioki-3217
I have a Fluke 107 I use for the same propose but it's bigger so I don't carry that one with me. You can take a look at the small Fluke 101,
it's not better then any $50 Chinese Dmm but I bet he may last you a lifetime and it's yellow like our Cub!
Look like I'm wrong....The 101 is the best $50 Dmm out there apparently....
https://www.youtube.com/watch?v=RBkjr3b5hQo