Since late last year.
Lomo LC-A purchased as working but it wasn't: Cleaned out battery chamber, re-foamed, cleaned internal switch contacts which were pretty gross. Probably will unload it as the vignetting at some apertures is too extreme for my taste. It does have an aperture lever, but that's really for use with flash and only works at a fixed 1/60th sec shutter speed.
Noblex 6/150E2 panoramic camera purchased as-is with dead electronics: Cleaned out battery chamber, replaced power MOSFET and driver IC, fabricated new brass bushing for shutter speed switch (seems to be a weak spot of the design and the bushing greatly reinforces it). Very solidly made camera and happily none of the semiconductors are proprietary, though I did have to do some parts substitutions. No foam! Heck of a performer but I'll probably unload this one too as I think my minimal panorama needs could be amply handled by something cheaper, smaller and lighter.
Olympus 35RC purchased as-is: Gross, it included a leaky old mercury battery! Cleaned battery chamber and fortunately there wasn't much corrosion. Cleaned and re-foamed. Might wind up flipping this one too as I've already owned so many FF rangefinder cameras.
Canon Demi EE17 purchased as-is from KEH: Not bad! The battery chamber looked alright, but once I got inside I discovered that the - wire had corroded and the solder itself looked strangely crumbly. Cleaned it up, replaced the wire but am I imagining things or is that battery contact made of stainless steel?? Rather than purchase special solder, I just fabricated a clip-on terminal out of brass sheet, though in retrospect I might've also tried one of those wire-glue types of products. The old leatherette sustained minor damage during removal as someone had really cemented it good! Tempted to replace with Aki-Akashi leatherette--surprisingly they offer it pre-cut for this model. Only seems to be one tiny bit of foam in this model, right around the finder eyepiece (hooray).
Olympus Pen S: Removing the top cover was an adventure! Could not find a how-to online for this specific model, so I followed someone's guide to one of the EE-series Pens which looked very similar in that regard. Removed the indicated fasteners but that cover was still holding fast. Dismissed the notion that there could be a hidden screw under the cold shoe, but in the end discovered that's exactly what it was: Spring clip actually pops out easily once you realize that it's supposed to, and right below it was the last screw. Finder was foggy with I-don't-know-what but it cleaned up OK. Cleaned, re-foamed and re-lubed, as some of the old lubricants seemed awfully dry. Applied a tiny bit of Molykote on a couple of metal-to-metal contact areas. Sweet camera: Love the size, controls are smooth, and it's got the quietest mechanical shutter that I've ever encountered.