Records with words with the letter S are slurred

+1 to Lewm's and Zd542's posts.

Everyone else is just guessing. One or more of these guesses may be correct for your case, or not.

As I previously posted and as these responses make clear, there are many possible causes. Which one(s) apply to your situation is unknown and unknowable without additional information.

In my experience what you are hearing is an artifact of mist racking. Some records are pressed "hot" and sibilance is unavoidable. Goodxalignment and set up are key and having a cartridge that tracks well also helps

Everyone else is just guessing? You have to start somewhere. Maybe Thefile will let us know who was right when the problem is fixed.

Time to upgrade turntable and cartridge.

Ha-ha. There has been a veritable torrent of responses and suggestions, whilst the OP is probably off doing something more useful (to him). I say, let this thread die until we have more info.