When we got home yesterday, we discovered youngest child had done pretty much nothing to get his car fixed and it was still stuck under the house (unable to change gear).
I did a bit of web searching, watched some videos from mechanics and found it's the shift linkage bushing (confirmed this morning when I pulled the centre console housing out).
Looks like I might actually be able to fix it myself, but am currently awaiting said child to breakfast and get dressed as he really needs to see what it is and how to fix it, for his own good.
