The elastomers in quadra 21r's are decomposing into mush. They are nearly 20 years old now so its only to be expected.
Mine went towards the end of last year and I couldn't find any NOS anywhere so I opted for a kit from suspensionforkparts.net
I got the medium not the hard compound and was very disappointed, just sitting on the bike compressed them almost to the end of their travel and the smallest bump had them bottom out.
If anyone can suggest a solution for this I'd be very happy to hear it.
I have a set with 1" threaded steerer if 1 1/8 isn't your size but like I said you'd need to get a set of the hard compound bumpers to get them working.
Quadra 21r's have no rebound damping so bumpy downhill sections are exciting.