Starter Noise Help??

[louky]

I just bought a neglected scooter. I can get it running but I am getting an intermittent noise when starting. It is fairly loud metal to metal noise coming from the starter area.
1) When the noise happens, all the lights on the dash dim completely as if the starter is pulling all the battery current on the bike.
2) I've tried a freshly charged battery and also a jump pack and see no change in the noise.
3) Sometimes, if I hold the starter in the starter goes ahead and starts the bike.
4) Sometimes it starts just fine without the noise. (20% of the time)
5) Once it is running I am not noticing any strange sounds.
6) It is also not charging (unrelated problem??)

I have a spare starter that I am going to swap out tomorrow to see what changes but I'd like to have any additional feedback for possibilities. I looked at the bendix today and it seems to be OK, but I also have a spare one of those to try if the starter doesn't fix it. Anything else?