1992 300TE not shifting from 2nd.

[threepoints]

I purchased the third Mercedes of our family a month ago. It's a 305k mile example of a 1992 300TE RWD that's been cared for well enough not to look its age. Although I have one problem with it I can't quite figure out. It shifts hard from 1st to 2nd but 2nd to 3rd it goes to redline but no shift. If I move the shift lever from D to N then back letting the engine RPM drop to 1200 it sometimes shifts on to 3rd and then 4th.
Sorry for the lengthy post but I figured I'd try to explain as much as there was going on. Please help, I'm contemplating admitting I made a mistake and sell it on.

Thanks in advance.