Sounds like bowden cable needs to be adjusted. Vacuum modulators are relatively cheap. If it shifts and goes forward in all gears without major slipping, then make an offer.

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1987 VW Jetta Mk II - Daily Driver
1992 W201 2.3 - sold
1985 W126 380se - sold
1985 W123 OM617.952 - sold
1981 W123 OM617.912 - sold
1986 W201 2.3 - sold
1979 W123 OM 617.912 - sold