Hi Barney,
I stumbled across these posts from a google search, I have a 2005 Bentley Arnage with a failed power antenna, the antenna can be extended fully by hand with little resistance, and retracted almost fully in the same manner but does not raise or lower by power. A new unit is NLA from Bentley, and I haven't had any luck tracking down any other replacement.
I'm sure this unit is made by some common 3rd party, but have not been able to determine who, and was wondering if it's something you'd consider working on?
I just joined this site, and cannot PM you due to lack of post count.
Thanks,