I cant seem to lift out the head rests. Mrs. wants to fit some decent seat covers. Fed up with the manky original discoloured blue panels when they get wet.
I have a hunch that the headrest system is not linked in the way the belts are (where electronic collision sensors 'fire' explosive charges to retract the belts). Instead, the headrest mounts are mechanically-linked to the centre of the backrest cushion, and hard pressure on that (which will happen if the car is hit from behind) pulls the headrest tubes forward against a spring, pivoting on a bolt at either side. See this cutaway from the parts listing where you can see that... https://www.fiatdalys.lt/diagrams/1B/1B64B73BE582323AC136D3979B77B32E.pngSomething to keep in mind as per my similar experience removing the headrests, and as explained by my local dealer service technician:
The front headrests have active whiplash prevention, so in a collision the headrests slam forward to keep contact with the back of the head and prevent neck injuries. That's why there's so much faffing about to remove them, and the owners manual therefore fervently dissuades owners of doing so (without explaining in detail why they shouldn't, or how they can if they absolutely need to). That being said, the anti-whiplash mechanism is linked to the seatbelt and collision sensors so even if the headrest isn't in place, it will probably go off in a crash, requiring replacement of the front seat headrest mechanisms (which is probably the least of your worries after a crash).
On re-reading this, I think the OP only wanted to remove them to allow seat covers to be fitted, and then to put them back again?...even if the headrest isn't in place, it will probably go off in a crash...