Shifter knob is loose
 

My 96 c280 gear shifter had become noticeably loose. I thought a spring in the shifter somehow broke or came loose because it happened overnight. The car has the 4 speed auto. I didn't make a big deal about it until going up a hill recently it apparently got out of the "D" position enough to apparently be slightly out of gear and cause a burning odor. If i'm not mistaken that's because the shifter is directly hooked up to the trans and not drive-by-wire like the newer 5 speed auto. What do you guys think needs to be repaired? Thanks.

I would check the shift linkage bushings. They are inexpensive, but a pain to install sometimes.

Vinamg