Started my car(190E 2.6) and the automatic transmission wouldn't engage. After moving the selector through the gears, I got the car to creep in drive although it slipped badly. It suddenly grabbed and I drove home. Car drove and shifted normally as it does now. Fluid is clean and full. Is this a fluke or transient issue or is my tranny on it's way out? Any thoughts. I really don't want to get stranded. Thanks. Transmission has 196K on it.