Re the 5-speed hubs: Are those the two cable versions with a bell crank on the left? The control for the bellcrank has a tendency to be unreliable, so what a number of people, including Sheldon Brown reccomend is to use a friction shifter for that cable and a regular 3 speed shifter for the drive hand side cable. If the stock shifter works great for you, use it until it wears out. http://www.sheldonbrown.com/sturmey-...spd.html#4and5

As far as the crank bearings go, why not pour some motor oil down the seat tube? This revives the bottom bracket grease. Just pour some in and ride it until oil stops leaking out. The 50s version of the Sports had an oil cap on the bottom bracket similar to the oil cap on the Sturmey Archer unit.