Pete , I see your only asking for brushes and bearings . Is this a common repair ? Reason I ask is this week the s/g on my PK stopped charging , still cranks . I took the one off the AC B10 in the mean time , the first thing I noticed was how much fast it cranks now ! I don't ever think it spun that fast lol I checked the ohm readings that I read online and seems to be in spec as far as the windings . I wonder if mine just needs for all the crap that's been building up inside for the last almost 50 years cleaned out and new brushes ?
Since most of these D/R are sealed for the most part (not ventilated), there is no way for the dust & grit from the brushes & armature to escape. .....This build-up does affect the operation.
Ball-bearings that are worn can cause the starter to crank more slowly. .....If the starter/generator is equipped with a bushing on the commutator end, a worn bushing can cause the armature to drag on the pole shoes, reducing cranking speed.
There are separate windings for the field coil, which are responsible for charging. .....If the field coils are shorted or "open", the starter may crank, but will not charge. .....The field current is controlled by the voltage regulator.
Don't be afraid to open one of these units - they're pretty simple. .....Just mark the location of the end plates relative to the main housing. .....To remove the drive-end cover, the pulley must be removed first.
I like to use brake cleaner to clean the components. .....It evaporates quickly, and does not leave a residue.
There are usually shims (washers) on each end of the armature, which may come off with the end plates. .....Just be aware of there presence & location.
When re-assembling, I found it easiest to insert the armature into the brushes on the end plate before sliding the main housing over the armature, then adding the drive-end cover.
Ball bearings, can be cleaned & re-lubed if they are not worn. ......Bushings can be replaced if they are worn, or lubed with grease. .....I like to use a little wheel-bearing grease, as that does not easily liquefy when hot. ......Too much grease is not good, and can get on the commutator & brushes.