I pulled one out of a 89 Sovereign in the bone yard today (along with my door latch) only to find the same issue as the one in my 90 XJ6. The little drive belt is broken. I search online and couldn't find a rebuild kit nor those little belts. Any leads here would help.

 

On my 1990 Sovereign, the antenna would not retract. I took the antenna mast out and found that the "drive belt" was broken. Bought a new one at my local independent Jaguar repair shop for around $20.00, more or less, installed it, and it works great!

 

I found some belts on line for $3.95 plus $5 for shipping. I hope they fit.

 

Antenna mast:

http://www.motorcarsltd.com/DBC2200.html

Always wise to get the grommet as well:

http://www.motorcarsltd.com/DBC2246.html

 

Little belts came in, I exchanged motors and the collector reel. I also ordered the grommet. It is in the car as good as new!