I know you are selling it for a friend so not sure how much legwork you want to do...but you could hop on to the owner's map, scroll down and find a short list of pinsiders that have Thunderbirds on their wishlist. Maybe you can find a match? One guy Cabal73 left a very good review of the game 11 months ago.
https://pinside.com/pinball/machine/thunderbirds/owners
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