stylus question

I have a shelter 201- about 6 1/2 years old on a rega rp3 plugged into the amp and just recently it is sounding really bad- lost all detail - sounds muddy like there is dust on stylus but i cleaned it. Is it time for a replacement stylus or could it be the phono imput on the rega brio-r? thanks
There may be gunk you could not easily clean off on the stylus. if it is mistracking too, then I would say clean it better. If it sounds like it is floating around and the sound comes and goes some. then i say it is 'stuck on' dirt.

If the sound is scratchy and consistent but really terrible, then you may have a broken diamond.

the diamond shank can pick up crap which is like concrete... really. Cleaning it off can be hard to do sometimes. Use the Mr Clean Magic eraser.
Clean the stylus good with Magic Eraser as Elizabeth suggests. If that does not help, check all setup and alignment guides again, make sure your VTF, VTA are correct, etc. If the problem persists, then it is possible that your stylus and/or suspension is shot and the cartridge may need to be re-built.
I second Jmcgrogan's suggestion. I've rehabbed over a dozen "broken" or "worn out" cartridges just by cleaning the stylus properly. The Magic Eraser is the best method for 90% of such cases I've found since I first wrote about it on this forum. In rare cases, stuck-on gunk needs more vigorous cleaning. A sliver of ultra-fine sandpaper will remove most anything that the ME won't.

By all means check your setup, but clean the stylus thoroughly first. Shine a light through the stylus and look at it with a magnifier. If the diamond is anything but brilliantly clear, it needs cleaning.
I just started using the Magic Eraser this week. I'd been using Zerodust for years. The Magic Eraser is so much better.

My cartridge is a London Decca Reference and it is notorious for wanting to see clean and unworn records.

There were records in my collection that I thought were unplayable with my cartridge. The records were clean and I thought my cartridge looked clean but it clearly wasn't. After a few cleans with the ME the cartridge sailed through those records that I previously thought were too worn.

Prior to using the ME my tracking force was set to the upper limits of the range and I was using a very steep VTA: all this in an attempt to keep things quiet in the groove and distortion-free. With my cartridge now perfectly clean thanks to the ME, I can choose pretty much any VTF or VTA that I want.

In addition to cleaning the stylus and the cantilever I suspect that the ME may getting rid of static. I wonder if the soap/chemical in the ME is coating the stylus and cantilever the way a dryer sheet, like "Bounce," coats clothing to prevent static cling.

In any case, it works fantastic.

Glad you're enjoying the benefits of effective stylus cleaning after all these years! I've lost count of how many "worn out" umpti-thousand dollar cartridges I've saved for people using this ridiculously easy and inexpensive method.

That said, I've never used or recommended the soap-infused version of the ME for stylus cleaning. The idea is to eliminate residues of ANY kind, both from our styli and from our record grooves. Soap residues may quiet the groove for a while, but eventually they'll become a magnet for dust and other gunk. Remember Gruv-Glide? Same effect, same problem.
The one I have is simply white through and through (no visible soap) but it isn't the "Original." The store I bought it at had three different kinds of ME: Bathroom; Kitchen; and 50% stronger. I went for the "bathroom" one. I will try some other store and look for the "original."