timer knob would not turn correctly to set time

I had my landscape guy, who volunteered to look at the dryer since he's also an electrician, come in and take a quick look. he turned the knob, pulled it off and told me the inside was cracked so it would not grab the turn mechanism. Who knew? I got the model number from the dryer door, checked in on the internet for Fridgedaire parts, found Partselect.com, ordered part, came next day, knob fits, dryer works. end of story. THANK U!!!