They didn't change much. Tom Servo was voiced by Kevin Murphy from seasons 2 to 10. Josh Weinstein only voiced him during the KTMA season. Crow was voiced by Trace Beaulieu from the KTMA season to season 7. Then Bill Corbett from season 8 to 10.
"For a long time now I have tried simply to write the best I can. Sometimes I have good luck and write better than I can." - Ernest Hemingway