Since 1992 (over 20 years) is quite a long time to store bottled wine. If you go to a supermarket or liquor store, you’ll notice that most red wines currently on the shelf date from 2013, 2012 or at the very oldest 2011. Yes, it’s true that American wine consumers don’t tend to age their wines but in a way it’s because most wines, except for the few truly exceptional pedigree vineyards around the world, peak after five years. If you’ve had good luck aging your Concord wines for that long, and still enjoy them, I applaud you. However, I have to think that your Concord home wine might have been better in the first 2-5 years of its life and not after 23 years in the bottle.
It’s no surprise that after 23 years a homemade wine will throw some sediment or become cloudy, especially Concord, which is naturally high in pectin. This is a natural part of the wine aging process and can get more pronounced as the years go on. As to clearing and re-bottling the wine I do have to ask one question: Do you like how the wine currently tastes? If not, clarifying the visual sediment will do nothing to improve the aroma or flavor. Additionally, clarifying with a fining agent, settling and re-bottling will do nothing but add more oxygen to the wine and will most likely destroy any good characters that might be lingering. My advice: Dump these bottles and make something fresher and less cloudy. Next time try using a pectinase enzyme after pressing (or follow the manufacturer’s instructions) to help remove excess pectin before bottling.