One of my Curados has a tension knob that works loose as it is used.  Any ideas on how to fix this?

replace the o-ring, p/n 28 on the schematic

you can use a plastic toothpick or a needle to remove the old one

Will the different types of Curados have different sizes of O rings?  I’m trying to figure out how to get one.

google your Curado model schematic and open the Shimano USA link - you'll find your p/n

 

this is Ambassadeur o-ring, but it's exactly the same idea.  

Over time, they flaten out and lose their grip.  

(I always have these around for Ambassadeur)

Thanks.  I looked around my workbench and found one that is a little thicker and put it on.  The knob is a lot tighter than it was.  Next trip I’ll see if it holds up.