LC III Caps Question

To the best of my knowledge, you can turn it on without too many problems.  Worst case scenario, it either won't boot or take forever to start.  Either case, the caps have leaked and you should replace them.  It's always a good idea to check the caps on any older machine.  

You should be looking to see if there is any leaking or crud around the caps, as well as checking the leads on the IC's.  They should be shiny and silver in appearance.  Capacitor fluid is corrosive and electrically conductive, so leakage will turn them black or green in color.  If you see any of this, it's a good idea to clean the board with alcohol, and re-cap it.  Honestly, I'd recap it anyway.  Even if you're lucky and the caps haven't leaked, they will.  So it's best to solve the problem before it's a problem.  

I used this set when I re-capped my LC III.  It's about $5, and it works great!

https://console5.com/store/macintosh-lciii-smd-tantalum-main-pcb-cap-kit-lc3-lc-iii.html