I have a 1984 300sd. The transmission shifter will not let me shift to reverse or park. This is what I have done so far. Took the linkage loose and veryfied that the linkage was not binding. I worked the transmission arm back and forth several times and the shifter worked several times, but is binding again. I do not want to apply too much pressure. Can I see and repair the problem with removing the pan? Thoughts and suggestions welcome. Thanks in advance. Jack Avant