[rastage]

Been running a Dual 1229 table with Shure M91ED cartridge for many years. A while ago, the right channel started dropping out. I was able to get it back by re-seating the headshell in the tonearm. Now the right channel is gone and won't come back. I tried swapping the leads in the headshell, and the problem dutifully jumped to the other side (left channel out). Next thing I tried was disconnecting the R and L leads from the shell and letting them dangle, then replacing the shell in its seat. I was able to touch each lead in turn with a finger, and got the expected hum from each side. Reconnected the leads to the back of the cartridge, no right channel. Does this mean that the M91ED has gone bad internally? Has anyone had a similar experience? (I also tried swapping in a spare headshell that had an M44 in it, which worked fine on both channels, so I don't think it's the connection in the arm itself.)

[FullRangeMan]

If you had a microscope you would check the stylus/cantilever since you use a removable shell/leads.

[thorman]

  There are always a ton of them on Ebay and very reasonable prices too. The M91ED is a good cartridge and much better with a Jico SAS Stylus. I would buy a nice condition used M91ED and go to LP Gear and order a Jico Stylus and you will be shocked at how much better it will sound...

[rastage]

No microscope. Do you think it's worth trying to swap a new stylus into the existing M91ED, or could it be a bad internal connection where the stylus enters the cartridge that won't work regardless of stylus?

[FullRangeMan]

I would not replace the stylus without have a good tech opinion on the internals.

I unaware a new cart price, but if its cheap get a new one.

[/mp]

Duckduckgo (anonymized google) is your friend:

vinylengine's cartridge database lists ~10 different M91ED variants. The suffix-less one shows a $180 MSRP.
A resistormag article says Shure ceased all phono cart manufacturing in 2018.
Shure's homepage doesn't mention phono cart's among its products.

Hope this helps.

[rastage]

UPDATE: After digging around in my hobby box, I found that I had another M91ED. I installed that into another headshell and put the 'suspect' stylus in ... sure enough, only one channel output, so I've concluded that the stylus is kaput. Beginning the search for a replacement stylus, appreciate any recommendations on brands to seek out or avoid. I've read a lot of references to JICO, but those seem to be on the expensive side. eBay lists some "unbranded" ones as cheap as $15. I'm looking for something in the middle of that range. Some folks think Pfanstiehl is good, others think it's terrible. On turntableneedles.com I see one by BLISS (part #761-DED) for about $60.

[FullRangeMan]

Have read good reports on Ortofon OM line MM cartridges, they looks odd and not cheap, but OM10 have instant user replacement stylus around $50eu.

[rastage]

Thanks, will keep Ortofon in mind as a fall-back, prefer to just get a stylus for the time being. Might get two, since I ended up with two M91ED's.

[S Clark]

You tend to get what you pay for with a stylus.   Depending on your overall system, a cheap Chinese $20 stylus may reach the limits of what your gear can unlock, or a $350 Shibata type might be absolutely stunning.    Your Dual is not the most resolving table, but I'd try to replace the stylus with as good as you feel comfortable spending. 
It's sort of like buy records.  You pay more for NM, but I've never regretting the extra bucks.  I've often wondered why I bought a VG+ record that I won't listen to.   
Look for bargains in other places than your records and your stylus.   

[JackD]

Pfanstiehl the company has been out of business for decades.  The original company bought OEM styli in bulk from the actual cartridge manufacturer and repackaged them in "rack" friendly packaging for resale.  They were found on a countertop rack in most record and musical instrument stores.  The rack usually consisted of replacement styli for the most popular cartridges of the day including Shure, Stanton, Pickering, AT and a few others.  If you new where and how to look you could periodically find NOS Pfanstiehl's on Ebay in their original packaging.  What's labeled Pfanstiehl now on Ebay are knock offs and are hit or miss.  The only reliable new replacements for Shure cartridges would be directly from JICO or from turntableneedles.com.