First, read Douglas Alderson’s Dorset A7 Club advice here and Roy Goodrum’s (Essex A7 Club) here. With aid of these excellent sets of instructions, I attempted to repair a non-functioning PA which I found had just two ballbearings out of the required 30. Also note:
The speedo pointer is noted as needing a pry bar for removal. I found that the pry end of some pincers worked, with a finger over the pointer.
You will get away with a standard small kit screwdriver for removing the 3 face screws IF you thin its end with a diamond pad or similar. The brass screws are not that small, but have a very narrow slot.
It is essential to unscrew the retaining set screw for the top brass bearing before removing. It will come out with effort if you forget, but you will entirely ruin the thread, making re-assembly very difficult. Do not ask how I know this.
Watch for other washers or added springs that might have been added in the recent past. I ended up with one that was not required, from past bodgery.
The ballbearings are available from David Cochrane A7 Components and also from ebay. Mine were magnetic and thus metal pointed tweezers were helpful initially, but when the grease stage is reached, a wooden cocktail stick helps when they get unruly.
Please share any other advice not contained in these three reports above, by commenting on this post.