Replacement Valve for AirHog Guppy Tank

Posting for a friend that it’s currently overseas and needs a replacement valve for his 10+ years old AirHog guppy tank. His valve suffered some type of non-repairable internal failure. Went to the AirHog page but it didn’t have any info. Emailed them an inquiry, but wanted to ask the Airgun Nation community if there are other sources or options for a replacement one.
Thanks.
Ray