I have a Collins Flashlight that was my grandfather's. It runs for about ten minutes on one full winding, but, because there is a little rust on the mainspring, I have to tap it against the palm of my hand when it stops before it has completely run down. I remember my grandfather disassambling it in about 1960, and re-winding the coil. (He was an electronics engineer at Westinghouse from 1919 to his retirement in 1963.) He told me that the mainspring is very nearlty the same as one in a thirty hour clock, but that he was never able to find an exact replacement, and didn't have the time or inclination to grind one down that was too wide.
My flashlight was painted red, and still has most of the paint, but, like Larry's, was dropped at some point in its life. I keep thinking I ought to straighten the ring, and get a new, uncracked glass for it, but, like lots of things, that is another project for retirement. LOL At any rate - I stumbled onto this site because last weekend my only bulb for the thiing finally died. So I was surfiung, looking for a 3/8" groove mount 2.6 (or so) Volt incandescant bulb. I think I may have found a source in Ken's Electronics, but he has a minimum order of 5 bucks, so I am gonna hold off and check to see what radio tubes I need to fill out my order.