So one of my tires is slowly leaking. I've had the core replaced and it still leaks. Instead of buying a new one, has anyone tried the service kit for one? Like sold here? http://goo.gl/UR9y6
The first thing I'd do is to see where the leak is coming from. If it's fast enough, you could probably just spray it with soapy water and look for bubbles. A bigger project would be to submerse the tire in water. It could be the valve, but it could also be a rim leak, or even a defect in the wheel. Since they've already worked on the valve, that seems less likely. Any shop that can mount a wheel is going to have the parts in the TPMS service kit. Whether they choose to use new parts every time they mount a tire is another question. I've got a wheel with a used TPMS sensor I bought from eBay. The used parts have worked fine.
I work at a school that teaches auto repair. They have tried many times as well as my local tire store replacing internal parts. The leak is coming from inside the step itself.