Performed furnace maintenance on 2001 Rheem system. Upon my maintenance I came across a few points of concerns 1. Found the indoor blower motor is leaking oil and was very dirty. Oil leakage could lead to the motor locking up or overheating 2. Flame sensor was in very bad condition due to age and corrosion occurring on it 3. Spark igniter had multiple hotspots and was beginning to show signs of failure 4. Single secondary motor control is beginning to become week due to fan motor over amping