If you don't mind removing the pin & tumblers you could slide a ball bearing in place a little bigger than the hole. Place a pin punch through the outer hole & tap it. This will slightly swage the rim of the inner hole so it will retain the tumbler axle.
This is an old machinist's trick for when a dowel pin won't stay in the piece its supposed but insists on pulling out with the other part. It works, just don't ask me how I Know!!

Miller/TN
I Didn't Say Everything I Said, Yogi Berra