DIY fix-it; wobbly batteries, memory cards, etc in electronics

For a couple months, my cellphone gave me much grief because the battery connection had gone wonky.  The phone frequently gave out at random, especially when I was using it for MP3's (which is often).  Then the memory card where I store the MP3s got in on the act, also beginning to wobble about and foil my attempts to listen to music.

I endured this with characteristic, quietly irate resignation until I came up with this:

- Open compartment and wiggle battery or card about until you locate the position where it functions correctly.
- Holding the battery/card in its ideal position, observe the gap between it and the edge of its compartment (this being why it keeps falling out of place).
- Take an old credit card or gift card, cut an aptly-sized tiny strip off it, wedge the strip in between the battery/card and the edge of the compartment to hold battery/card in place, and voilà! free solution to a noisome and potentially costly problem.