I bought my 2002 XKR coupe 18 months ago up in Sydney. Included in the paperwork was an invoice for work done on the car by an authorised dealer up in NSW back in 2009. The work included:
"CHECK DRIVERS HEAD REST OPERATION - STUCK IN UP POSITION removed offside seat and stripped cover off. Removed head rest motor and checked. Found head rest motor gears to be stripped. New motor required to rectify fault. Customer requested old part to be re-fitted. Total for job $210 plus GST"
Fast forward to 2016 and I am getting the headliner recovered so I have removed the front seats to get the headliner out. Having read many of the posts on this forum about fixing recalcitrant head rests I thought about the dealers words of wisdom and decided the "stripped gears" did not sound quite right. So I peeled back the seat cover, pulled the head rest cable out of the motor and wound the head rest (that was still in the full up position) back to fully down just in case my fix didn't work. I then carefully cut 12mm out from near the middle of the cable sheathing as per the official Jag fix, roughened the ends around the cut and following the lead in Reverend Sam's very informative video, used 2 sections of heat shrink wrap, short one on the join then a longer one over the top to re-join the sheath.
Today I finally got the seats back in having finished the headlining replacement so imagine if you will my joy at finding my cheap fix has worked. The head rest now raises and lowers beautifully. No stripped gears on the motor. I think the heat shrink wrap cost me A$12 for a pack of assorted sizes. There is a moral here somewhere....

 

This is what drives people mad with dealers. They knew of this tsb yet still wanted to charge for a non existent motor problem as associated costs.

 

I worked for one of the worst 6 months of my life at a Ford dealership as a service adviser and the service department was built on the premise of get me a car in for anything and we can make a grand off anybody. I saw whole AC evaporators changed costing $2300 for remove and replace when all that was wrong was a vacuum motor you could change through the glove box door. There is a good reason I tell anyone who eyes my 2004 XK8 , don't even think about it if you have to use a dealership for anything.

 

The more you read and study this forum, the more "secret" $5 and $10 fixes you'll learn about and be able to do yourself. Being able to DIY just about everything that pops up is critical for owning these cars....