Hi Colin,
I have two suggestions which might help, one I have already done to mine and the other I'm about to get done.
First is a bit of a bodge but works fine: Inside the seat back is a roller covered in plastic tubing which runs up and down as the headrest is inserted or removed, over time the plastic hardens and becomes becomes square where its been resting on the headrest support, this makes it jam up when it should just roll
I have taken a sharpe knife to mine and removed the plastic covering all together, just leaving the metal roller and now the headrest slide in and out without any resistance.
If you look down the seatback through the headrest opening you can see it quite easily.
The next and more professional step is to have Allon White to add headrest pockets to my tonneau so that I can leave the headrest in place and fit the tonneau over the top.
I'm sure there must a trimmer near you who could do that too
Hope this helps
