I am the new owner of a 1997 S90 in mint condition with 117,000 miles. When the car shifts from 1st to 2nd, there is a noticeable hesitation and shudder, then it goes smoothly after that. The same thing happens on the down shift from 2nd to 1st. I was told by the previous owner that the problem is in a sensor, and not the transmission. Any help out there?