I fixed my starter! For some reason when I got the bike out earlier this year, the starter wouldn't run. I jumped across the two terminals and the starter went, so I knew it was something else. I thought it was the solenoid so I took it out and tried to take it apart, which ended up with me breaking it. It doesn't seem to like to be kickstarted early in the morning, so I have motivation to fix it. A new solenoid is ~$50, so I swiped the solenoid from my KZ750 and put that in. It still didn't work, so I traced it to a bad connection in the headlight bucket.
The starter clutch in my KZ is toast, so I didn't need the solenoid anyway.