So I have been having some problems with my a/c fan/blower. First, I lost several speeds on the dial. Next, I only had 5 (high). Finally, it would not shut off until I turned the key off and once in a while it wouldn't turn on. I know that is is the blower motor resistor and will be replacing that this weekend. Today I get in my truck and the speed selecting dial is frozen. It wouldn't budge. I popped the plastic dial off and still couldn't get it to move. I eventually turned it a little harder and got it to move. Now it feels like I am not able to select the speeds accurately since I could feel a "click" before. Any body have any ideas why that would stick?

Addition: 2004 Chevrolet Silverado 1500 5.3L