[TR] Brake master cylinder and bleeding the brakes.

[Randall]

> Would it make sense to try to polish the bore to a mirror finish?

Worth a try, IMO.  You have to get it so the piston will return reliably
under just spring pressure.  Might also be worth checking or replacing the
spring.  The springs in the single-circuit masters have been known to weaken
or even break, I assume the dual circuit masters can have the same problem.

> What would I use to achieve this finish?

One method:
Piece of hardwood dowel from Home Depot, slightly smaller than the bore.
Cut a slit in the end and stick a piece of fine abrasive cloth in the split.
A few drops of water or oil might help.  Keep polishing the bore with that,
as the abrasive wears out.  If that doesn't get it smooth enough, repeat the
process with strips of even finer sandpaper.

Randall