Start by getting a hold of a vacuum line diagram for your specific year and model car and making sure that your vacuum system matches it exactly. If I'm not mistaken, the shift quality and load is all controlled by vacuum in '82. The bowden cable came along later.

If your vacuum system is screwed up, you'll get very firm shifts and you can get the shifting much earlier than you want it to be. Start with the basics: make sure your vacuum lines are all going where they're supposed to be. Your photo shows several lines open or what looks like broken.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)