NOS Shure V15 type III cartridge opinions


I know this sounds crazy but going thru boxes stored in closet for the past 40 years and found one of these I had purchased in 78 as a spare and never used. My question is should I open it up and give it a spin on my vintage TT or keep it to replace my in use cartridge until it goes south or open it install to see what happens? Wished I had another headshell. I read this was the best mm cartridge build, great all around sound and unsurpassed tracking. 
Or put on market? I'm leaning toward trying it out but then again?
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I had the elliptical stylus and later replaced it with - I think - the MR (but it could haven been the hyper elliptical). The update was a real improvement with a sweeter and more detailed sound. It was an excellent cartridge, but required precisely matched capacitive loading. At the time, Quad made special inputs boards for them, to match loading and output level. Tracking even at low pressure was exemplary, frequency response (if loaded correctly) was very flat, and distortion was low. However, the expert opinion (including that of Shure itself) seems to be that these days no original stylus assembly can still be in good working order - it will have dried out.
Use it!  The VI iii is an excellent cartridge. My Son has one and uses it daily. Wonderful dynamic and well balanced. 

N. 
Thank for the input. Consensus seems to be that the suspension for the stylus may be suspect after all this time. I did visually inspect the cartrige and stylus with a magnifying glass and see nothing visually other than that it is pristine.  Just in case I did look for a replacement stylus and found only aftermarket stylie ranging from 13 to 88 dollars. A Phanstiel, supposedly made in switzerland, is 25 dollars and the highest priced ones are from Japan and shipped from there. Does anyone have any experience with these aftermarket stylus?
Any information would be helpful and appreciated

Aftermarket styli vary enormously in price and some are outright bad. The Japanese Jico ones have a good reputation. Shure themselves recommend their M97xE cartridge as the best replacement.
As an anecdote, I recently noticed that the audio archive of the British Library use the Shure M44 cartridge for their digitization of some old recordings, using specialty styli: https://www.youtube.com/watch?v=yI5DYJPSf-A&feature=youtu.be&t=162