Flashlights. Why do you have to knock them or shake them?
For them to work. Tried putting tin foil on the spring connections.
But that didn’t work?

The battery contactors are corroded. Get a small LED flashlight, they have push buttons. In the meantime, clean all contacts with light 400 sandpaper.

The battery contactors are corroded. Get a small LED flashlight, they have push buttons. In the meantime, clean all contacts with light 400 sandpaper.

Thank you. Harbor Freight Product

Harbor Freight ProductThere's your problem. HF is junk!

I found out long ago, with flashlights you need to spend a little more to get anything decent.
Surefire, Fenix, Nitecore, etc are great! Only they are quite expensive.
Streamlight is also great, but pretty reasonable. Some are even made in the US.

The only time I buy from then is when it's a one or two time use. Many of their products should be considered disposable, like a lighter. Use it until it stops work and then pitch it.

You beat me to that one. You shake or hit them because the cheaper lights do not always have good connections. Weak spring, batteries left in too long,

Good, better grade flashlights do not normally do that