The photos below are of a long-cage Simplex SX610 that I received today from an ebay seller. It seems to be in good shape, with one major exception: the "lips" on the end of the mounting bolt are completely rounded off, evidently as a result of someone mistaking the spring tensioning fitting for the mounting bolt. As I hope the photos make clear, the flats are completely rounded off, though if you look closely you can see where they once were.


Oddly enough, the spring is not broken, and the derailleur stop plate is completely undamaged. My guess is that the ebay seller discarded the original stop plate and replaced it with an undamaged one (maybe innocently; as my previous post, "Humbled by Simplex" made clear, I'm no Simplex expert myself).


In a post of a year or so ago, headed something like "Real-world capacity of Simplex 6600," verktyg noted that its sometimes possible to repair that kind of damage with a taper punch; I'm also attaching a couple of photos from that post, with his annotations in red.


Does anyone know how that could work? My guess is that you position the stop plate over the remains of the lip on the bolt, then tap a taper punch into the hole to re-form the lips, with the plate acting something like a forming die. But I'm not sure how that could be done without destroying the interior threads in the bolt.


I'm undecided about whether to send the derailleur back to the seller. I got it at a reasonable price, and it's not like there are tons of them out there. If I could only find a trashed SX610 with an intact mounting bolt, I'd be in business. I supposed it's too much to hope that anyone here has one that they'd be willing to part with....