transmission help

What is your question?

Was driving on the road, changed lanes and pressed on gas to pick up speed and all of a sudden nothing. Car was still on, tried giving it gas and car wouldn't drive, the rpm was going up while I was giving it gas and still no movement, felt like it was in neutral. Car has been periodically maintained, miles is at 281,000, majority of miles is highway and this is the first major problem. I took it into aamco and below is what they stated: Our initial vehicle check revealed that the transmission fluid level is OK and the condition is varnish with the burnt odor. test drive revealed no movement front or rear, noted bearing and pump whine present coming from transmission, noted no line pressure during testing a computer scan revealed following code PO716 input speed sensor circuit PO721 output speed sensor circuit, recommend tear down Are they about right to do a tear down and replace soft parts (that's what they called it) or is it just speed censor circuits?