mradowic,
The signs of a dying steering lock/tumbler are easy...It will start to be "loose and rattly", not tight and solid like a new one, and the key may be hard to turn or will tend to stick in one position from time to time. The longer you let this go, the worse it will get, and the more likely that it will get stuck completely. If that happens, it will have to be DRILLED out, which is a big, expensive pain in the a$$!
BEFORE that happens, it's easy and inexpensive to remove and replace it yourself.
Mike