Numrich and S&W both should have the right parts, but S&W won't sell you one.
Another good source for used parts is Jack First.
http://www.jackfirstgun.com/
When you order, make sure to provide the exact model INCLUDING any dashes in the model number. As example you have a Model 10 no dash, 10-1, 10-3, etc.
One word about revolver extractors: They are NOT "drop-in" parts, and used parts rarely can be fitted since they've already BEEN fitted to a different gun.
When a revolver needs a new extractor, the extractor is first fitted to the cylinder, then the entire unit has to be machined to fit the frame.
This is a complex job involving adjusting the head space, cylinder end shake, barrel/cylinder gap, and alignment.
It is NOT a job for anyone but a real professional S&W qualified pistolsmith, and most local gunsmiths AREN'T.
My suggestion is to stop spending money on wrong parts that likely won't be usable anyway, and send the gun in to S&W for a PROPER repair.
They have the RIGHT parts, the special tooling to do the job, and the experienced gunsmiths to do it RIGHT.
Price and turnaround will be very competitive with local gunsmiths, and you'll get the job done the right way.
Again, most parts you can buy WILL NOT fit correctly. S&W will not sell new parts unless they're factory installed.
Local gunsmiths can often "get it working" but seldom get it RIGHT.
