I have random hard upshift: 1->2, 2->3, into D. Sometimes it shifts smooth, sometimes it shifts hard with shake and bang.
A mechanic said that that hard shift was acceptable on old car, but I sometimes have harder shift than the hard shifts I had while I was test driving with him.

Vacuum modulator was recently checked. It holds vacuum, and was adjusted a little. Modulator dustcap was also replaced.
Then am I done with vacuum stuff?

Or is it worth checking vacuum lines in accordance with the vacuum routing diagram, and check whether there is crack on connection?

Is there the vacuum routing diagram available online or on MB service CD? I could not find one at alldatadiy or MB service CD.

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.

Before someone gets upset....
Please do a couple of searches on the topic.

Hard shift

Transmission vacuum

Hey folks, I could use some suggestions.
I am drawing a blank? what a strange idea. LOL
Must be typers block. LOL

__________________
ASE Master Mechanic
https://whunter.carrd.co/

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
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Dynamometer.
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Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
2003 Volvo V70

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You absolutely are not done. The vacuum modulator on the transmission is actually the last thing to be touched or adjusted when solving vacuum/shifting problems. Go buy a miteyvac vacuum tester, do some reading, and go to work. My transmission started out as junk, but after much tweaking and tuning of the vacuum system, it's like butter all the way through the gears, and I never needed to change the modulator. This with 255k miles.
Here's something to get you started...

http://transmission.articles.mbz.org/adjust/