I have two psv10's and I think both are from 1984 by looking at the serial numbers. (on arrival)

On one of them the ATAX stem took me around 6 months to free.
The seat post on that bike is the expander bolt style, and because the seat clamp is plastic I can't work enough force to get it to turn. Thankfully its stuck at the perfect hight for me so there it stays.

The other bike has a grub crew on the seat tube and a philippe stem, no problems.