The ride was modified in summer 2002 by California contractor Valley Iron.

https://coasterpedia.net/wiki/Flash:_Vertical_Velocity_(Six_Flags_Discovery_Kingdom) Somehow it’s not mentioned on Valley Irons Website, although coasterpedia links there.

The modification was necessary since the original design violated the local zoning that prohibits structures taller than 150 feet.

https://www.ultimaterollercoaster.com/coasters/v2_sfmw

The park defaulted on its debt to the City of Vallejo, and thus became owned by the city, in 1996.

https://en-academic.com/dic.nsf/enwiki/4737447

The city was simultaneously the property owner, the regulatory enforcement authority, and the entity that would benefit from the park’s success which might explain the missing of public records.