Replace Stylus or both Cart. & Stylus??

I ressurrected my old technics SL-Q2 turntable recently after 20 years of storage, sounds ok but seems to change sound quality with different LPs. I'm thinking maybe the stylus is in need of replacement (SHURE N95HE in it's original Shure M95E PHONO CARTRIDGE). Do need to replace both or would the styus replacement be sufficent? I have a line on this stylus new believe it or not.... Opinions??
You just need to replace the stylus, which on a Shure is actually an assembly consisting of the stylus, cantilever, magnet and suspension. All that's really in the cartridge body are the pickup coils which should last indefinitely with normal care of the unit.

I don't know if that will necessarily correct the problem you're having though. Perhaps.
Shure says their cartridge shells should last 50 years or a lot longer if cared for. They are after all sealed and have no moving parts. So you should not worry too much about the cartridge.

The only aging issue is the rubber that is part of the stylus assembly. I tends to harden with age if not stored well. If it sounds good to you, maybe it is OK.

The only problem is there are no genuine Shure stylus available anymore from Shure. Most dealers no longer have it. I believe I saw some from that were original (not generic). Also check Needle Doctor. They show them on their website. I have no idea how good the generic replacement stylus are. Some are from Japan, others from Switzerland. The generic replacements probably are just eliptical "E", not HE. But so may be the Shure ones at LPgear and NDoctor assuming they still have them.
There are rubber components in the cartridge assembly that could have dried out over 20 years. I remember they are part of the stylus suspension system, but I don't recall if they are located in the removable stylus piece or if they are located inside the cartridge body. Can you tell by looking at the stylus unit? Obviously, if they are part of the stylus unit, that's all I would replace.

Before you do that, consider that there may be other reasons why the sound quality seems to change with different LPs. For example, you may be aware that some LPs are significantly thicker now than LPs of old, and the difference in thickness results in a change in your vertical tracking angle (VTA). This in turn will affect the sound quality of the playback. You may be hearing that difference, or there may be something else. There might be nothing wrong with your stylus and cartridge. Good luck.
It may just be the LP"S some are recorded and sound beter than others.
You should also download the free alignment protractor from the vinyl engine, so that you can get your cartridge correctly positioned in the headshell. This may very well be the cause of the changes that you note.

There will be nothing at all wrong with replacing just the stylus assembly, and that should be a very simple task. However, for just a bit more money, you can get yourself much better performance. For around $60.00 the Ortofon OM-10 is a good place to start. It will sound brighter than the old Shure. It can also be upgraded, at a later date to their more expensive models the OM-20, 30 and 40 for just the difference in cost of the stylus assemblies. For around $90.00 the Shure M97xE is their current cartridge. It sounds much, much better than the M95 and has the darker Shure sound. Moving on to around $100.00, the Audio Technica AT440ml is really nice, a bit bright and maybe the best of the lot, but there can be problems with VTA in tonearms that do not allow for this adjustment, such as yours, and there have been some anecdotal reports of quality control problems as well. The Grado Red can also be had at this price; I don't like their less expensive offerings, but this is a good example of the Grado sound.

While you are there, you may want to try a free, and reversable, tweek. When you remove the headshell, you will see that there is a little rubber gasket on the collet of the headshell. Try simply removing this part. You may very well find the sound to be more direct, or more irritating. One man's meat....