Update:
Asked Keystone for a replacement bolt. Told to take it to a service center. Contacted LCI customer services. They mailed me new struts and bolts.
Note: to install new struts/bolts, stairs must be all the way up.
FYI NAPA auto parts stocks the ball studs (that's what broke).
10mm ball stud. 5/16" - 18 course thread.
NAPA auto parts.
Part#: BK 735-1896
Lift support mounting hardware.
https://www.napaonline.com/en/p/BK_7...Input=735+1896