In the Sternbach/Okuda TNG Technical Reference Manual, there's a footnote that Gates was concerned with getting medical procedures right, how the equipment supposedly worked, etc. The medical tricorder section of the book was based on notes she asked for regarding all the little buttons and labels on the prop and sequence of operation.
The main reason Gates was fired was because she cared too much about the script and pointing out plotholes while episodes were being made. Gates had an extensive production background and cared about her character. The producers (Rick Berman excluded) got pissed like the morons they were and sacked her.