Timer Not Cycling

Gas dryer is 8 years old. Original timer wore out recently, so replaced with new timer. Worked fine for 3 loads, then on 4th load display light always shows clothes "damp" and timer never moves off "normal dry" setting. Dryer runs and drys even though timer has never moved. Replaced the sensor bar in the drum and the dryness display assy circuit board, but nothing has changed. What else could be the trouble? According to the wiring diagram, this should have repaired the dryer. Help! Thanks.