Here's a simple, but very commonly requested modification - replacing a built in cable like this Shure 520D had with a Switchcraft connector. Although this seems like a simple mod, in fact it is not as straightforward as you might think.
The 2501MP connector was designed as a "panel mount" device. It comes with threads and a raised knurled portion on the part you can't see in this picture. The knurled part is for use when the connecter is pressed in to a properly sized hole. But the shape of a mic shell makes it very difficult to support while pressing the part in properly, so most pros turn or grind the knurled part off. However the hole in the mic is usually still too deep to get a nut on the inside, so it must be drilled and tapped with the proper threads. The connector is then threaded in and secured with Loctite.
Then there's the matter of a ground connection. You have to electrically connect the shell to the ground side of the mic element. The 2501MP comes with a solder lug but this won't work if you can't get a nut on inside the shell. In that case you have to drill and tap a small hole somewhere, crimp/solder a lug on the ground wire and anchor it there.
There's no rocket science to this stuff, but the investment in proper tools and some experience are why folks sometimes pay people like me to perform this service for them. I have several thousand dollars invested in my shop tools, including a lathe and milling machine, electronic test equipment, temperature controlled soldering station, arbor press, and many custom jigs for holding/fabricating/assembling.
The pictures below show some "before and after" conversions. Both of these required precision machined threaded inserts to mate the Switchcraft connector to the original socket housing. In addition internal modifications were required to support a grounding connector.
