I see this problem still seems to crop up a lot on the forum. I am pasting a link from our jaguarforum uk brothers, that I found that enabled a cheap fix to the problem. Easy to follow instruction and Photo's, I am sure they will be glad we took advantage of it. I did mine no problems since, good luck may make a useful DIY Sticky.
https://www.google.com.au/url?sa=t&r...59568121,d.dGI

 

You know, mine's been doing it for so long I forgot it clicked!

 

I recently bought a X type 3.0 with the same problem.

How I fixed it:

Carefully pry open the original microswitch and LIGHTLY sand the contact surfaces by putting a small strip of thin sand paper and then pulling it out. You can put a VERY thin layer of conductive anti corrosion grease (copper grease) to help with operation as well. What's happening here is that the contacts that make a complete circuit when the car is out of P and R can arc during opening and closing and this arc creates a layer of oxides that prevent the contacts from conducting electricity.

No money spent and no cutting/soldering wires!!