No Forward Engagement, Reverse Okay

Check fluid level, drive axles, shift linkage, low internal pressure, oil pump external or internal (support sealing rings) leakage, filter or filter seal, valve body malfunction (gasket damaged or off location, stuck regulator valve, 3-4 shift valve, forward clutch control valve and 2-3 servo regulator valve), forward clutch assembly, low one-way clutch, low-intermediate servo assembly and output shaft splines damaged.