I had a rebuilt automatic transmission installed last year in my 1991 300D. After a month it developed a hard knock when shifting, both up and down. I brought it to the mechanic, who said it was only a vacuum line loose, and it has been fine since until....

IT has started doing this again last week, but I have divorced this mechanic for other reasons.

Is this common and where do I look for to re-attach/replace the vacuum line??

Thanks.....

Wayne