Welcome to the forum, Toni!
You can tell if a mandolin’s bridge is in the correct spot by checking the intonation: Play a harmonic at the 12th fret, then fret the string at the 12th fret. If the fretted note is flatter than the harmonic, the bridge is too far back. If the fretted note is sharper than the harmonic, the bridge is too far forward. The goal is for the harmonic and the fretted note to match.
So sorry to hear about your Gibson mandolin, by the way!