Hi, I just acquired recently a second hand original Lodestar and was having the same issue.
I then found the ASCOM driver GitHub, developed by Bret McKee, through the ASCOM portal - Camera & Video Drivers (ascom-standards.org)
It seems a new version of the ASCOM driver 6.3.1.23042 was published in Feb '23 while Starlight Express page is still referencing to an older version 6.2.1.18182.
Releases · brets-astro/sxascom-releases · GitHub
After installing the new ASCOM driver the issue was solved and stars are totally round using bin 1 without the need to update the camera firmware.
SE should update the driver on their web page.
Hope this helps, all credits to the developer!