Who can analyze the condition of my old cartridge?



I have inherited a group of four older MC cartridges and would eventually like to sell them off to upgrade my own system.

I'm looking for a business or audio shop that will evaluate them for stylus wear and compliance on the rubber bits. I want to make sure I'm not selling junk. But I'm hesitant to send them to the re-tip shops, as I'm just interested in current condition.

Must be a reputable US company or shop who knows what they're looking at. No local options in West Michigan.

Seems like a lot of people would have this same need. Any suggestions?
montague2
Nsgarch, Its the vinyl engine forum, go to cartridges and do a search under "nude pictures" one gentleman has done amazing work with a kids usb camera.
Shure sold a microscope setup for assessing stylus wear. Their 'scope was 200X, with two side lights to illuminate the stylus' surfaces that contact the groove. The manual that came with it had photos of new, slightly worn and worn out styli for each different type of stylus (conical, elliptical, etc.). You compared the photos to the stylus being examined. Even with this equipment, it took some experience to properly assess stylus condition.

I just finished reading a good article on stylus wear in a 1980 "Sound Canada" magazine. The writer used to work in the pressing plant of a major record manufacturer. He said that the quality control people could replace styli on test turntables when they felt it was needed. He examined rejected styli using good equipment, and often could not determine any wear. So he did some blind testing with QC people, and they could tell a new stylus from a rejected stylus without fail. His conclusion was that the best equipment and an experienced tech wasn't as reliable as experienced ears when it comes to identifying stylus wear.
I didnt know about that shure system Id love to see the manual. I have a B&L stereo 7 with a dolan jenner dual hologen light source that gives magnification of 140X (with 20X eyepiece) I have heard people inspecting with 50X but my experience is that you need much more magnification to really do a good inspection. I have found flats at 140X that could not be seen at 50X and were audible. If those QC people could hear wear that was undetectable under 200X that is amazing. Thanks for sharing that story.