Washer is not agitating in whites and slowly in colors. What and how do we troubleshoot?

1) Verify a circuit breaker isn't tripped

2) Advance the timer control dial slowly 360 degrees-

If the washer starts spinning, then we know the motor and drive belt are fine but that there is something wrong with either the timer control dial or the agitator solenoid. Call in a professional for this.

If the washer doesn't budge, then verify that the drive belt(s) is attached and not broken by removing the back panel. If the belt is broken, replace it. If it is loose, then tighten it by loosening up the bolt holding the motor and moving it on its swingarm (much like a car alternator) until there is a 1/2 to 3/4 inch deflection in the belt.
Some washers use reversing motors. It's possible the motor works on the spin cycle but not on the wash cycle. If so, call a pro.

3) Visually inspect the lid safety switch- Is it loose or cracked? If so, the washer might work intermittently, stopping at different cycles.

4) Check motor and drive belt- Remove the main access panel (usually in the back). Is the motor spinning, but the drive belt isn't? If so, then you have a drive belt problem.

My washer and dryer combo does no agitate and when i turn on the dryer it turns on the washer but does not agitate.