I recently purchased a Hamilton Spectra for just a couple of dollars. When I opened the case, I found a leaked dead battery and corrosion to the parts beneath. To make a long story short, I would like to replace the works (although it runs), but am unsure as to what caliber movement is correct--most articles refer to a 500 movement, but this one is a 505. Were both calibers used? If so, what specifically should I look for in a replacement (i.e.--caliber, movement numbers, etc.) and where might I find one? I've tried eBay, have so far been unable to win one (I have been bidding on the 505's, but now I'm not sure if that is correct!) Thanks for any help!