Thanks for all the replies and advice.  I did forget to mention that it was the mains I was asking about (in my mind landing gear is the mains and nose wheel is the nose wheel, but obviously that left too much undefined.  My apologies.) .  Thanks Alain, I had called Matco and already ordered the new seals, but the consensus seems to be that if they're not leaking, changing the seals probably won't help that much.  The other point seems to be that if light finger pressure is all it takes to make them over-center that is good enough.  As mine will overcenter if you give them a minute or two or right away if lightly pushed, I'm now of the opinion to leave well enough alone  A bit of yaw would be more than sufficient to pop the over-centers. Vern suggested that I might want to entertain changing the Matcos to the currently supplied Wolstenholme cylinders, but now that I'm sticking with current situation, I think I'll hold off on that change. With regard to the brakes.  The Matco customer service mentioned to me that they rubber mallet the calipers after assembly to straighten the bushings to plate alignment.  This could be exactly my problem as I had remade the bushings in SS (which interestingly enough, Matco also now makes the bushings in, too)  recently and reassembled.  So today I took along a rubber mallet and smacked them lightly. They seem to act better, so pending contrary information, this also will be a "leave well enough alone."  I will keep in mind the advice to change to Groves in the future if I continue to have problems.

Regards,
Charles Patton