(later)
It seems I got lucky. I cleaned the lens and reseated the (three, I think) ribbon cables, it came to life on the bench, and now it's working in the car. I'm not about to declare it "fixed" before taking a few long drives on rough roads, but at the moment I'm pretty happy.
The tool I use is a 14mm hex on a socket. So I lean on my breaker bar and give it a good shove to crack it free.
Fair call on the rebuild. When you were talking bearings I thought your plans had changed!
Cheers
Bennie