The shifter assy. has a few plastic bushings.
I think it was 3 bushings on my ZF.
These are gone after 15 years and the shifter assy.
doesn't work correctly as it should, i.e. the shifter is in N,
but the tranny has still the D gear.
The bushings are very cheap app. 2 $ a piece
and my indy mechanic installed it in 10 min.
All together about 20 $ with an indy mech.
If you go to Volvo I think they calculate at least 1 hour
(including some storys about "adjustment" and so)
plus parts and so on, which ends up at 200 $ or so.

The symptoms go worse with every day until U can't find a gear at all.