Three battery doors from Nikon SB-800 flashes (or Speedlights) with cleaned up and polished contacts. Minor signs of pitting on one from the leaking cells that were left inside the flash, and a bit of hinge plastic was broken off another. The doors are the easier bits to clean, but I've managed to clean up the other contacts that at the deep end of the battery holding section. The battery contacts of the fourth flash didn't need cleaned, as its problems are related to firing the tube. Two of these now working units are a bit scruffy with scratches etc. on the outside, and I going to keep them, as they'll be fine enough for me and my light usage of flashes, and I'll sell-off my near pristine pair that I've had for years.

Battery contacts of one of the two SB-700s cleaned up like new, which matches the rest of the flash unit and all the standard bits-n-pieces that it came with. Hadn't realised that these are still a current model, and it should fetch a good price.

For all the flashes, also cleaned and polished up the flash mount and contacts area, as this is a place that often gets mucky and can cause bother if not looked after.

If you do have a flashgun/speedlight somewhere, that you don't use often, do not leave alkaline cells in it, as those cells will eventually leak, and that seems to be the #1 reason why these units stop working. If that advice is too late, fear not, as the chances are the unit can still be saved. It'll just need a little careful work by yourself (or me!) to do so. This also applies to other battery powered equipment. #2 reason for your flash not working may be physical abuse/damage from dropping it, resulting in some internal damage - broken: wire; flash tube; or mechanical part. Remember, keep the mount and its contacts clean, and dry too.