Hi
Does the alternator need to be removed to change the brushes ???
Are they straightforward to replace ???
Cheers Dave
It would be easier if you remove the stator and work on it on the bench rather than on the bike. The Stator comes off easily, just undo 3 nuts and 3 connections and pull it off. You don’t need to remove the rotor.
The only tricky bit is the soldering of the wires if like me you have a great hatred of soldering.
Don’t absolutely have to take anything off, I’ve done it in situ. But as Don says need to unsolder the old wires (copper braids) that are attached to the brushes and then solder on the new ones, and needs a fairly powerful soldering iron. Plus solder obviously. Also you will need to remove the catherine wheel shape coiled springs to extract the brushes, but be VERY CAREFUL that one doesn’t fly off and get lost (guess how I know! 
) If you do lose any I’ve discovered the starter motor brush springs are exactly the same so can search for that in a catalogue or price list (online or otherwise) if necessary.
HTH
I’d go with Don.
Easier to work on the bench than bumping your head on the forks 
Also gives you a chance to clean the brush housing and blade connectors on the stator while you’re at it.
As Mike says you need a good soldering iron. Too low a wattage and the heat will simply dissipate. You’ll need some solder too. I only say this after a rescue mission with a neighbour who assumed that soldering irons would solder!
Good luck
Steve
I am probably recalling an earlier time when I could crouch down for things like that without getting galloping cramp AND be able to stand up again afterwards
You do not need to remove the spring, just hoik it out of the way.
You can also solder small washers onto the end of the brush wires and, after cutting the old ones out of the way, hold them in place with the bolts already there.
The positive brush must be on the insulated part of the bolt.
Well I ‘hoiked’, it ‘went’ …
Washers good idea. Even more posh, kosher electrical solder-tag washers.