I have a Kenmore GE Gas Dryer Model # 110.70932990 that is 8 yrs old. Recently, it stops in middle of the drying cycle. Sometime when I restart the cycle from start it completes the cycle. Also, sometimes the heat will not come on. I have check the lint areas in the dyer and they are clean. I have not removed that back vent 3-4" pipe to see if it is blocked. Any ideas? Electronics, motor, vent? Thanks