After turning off LG washer and water supply, I consulted internet and diagnosed origin of problem as either the Water Level Pressure Switch or the Inlet Valve Assembly. After watching excellent videos on repair of each problem provided by AppliancePartsPros.com, I decided to replace both possible defective parts rather than take a chance of making wrong choice. I ordered parts from AppliancePartsPros.com, they arrived the next afternoon, and I replaced the parts as instructed by video the following day. The LG washer now works perfectly with
the water level well controlled.