i used to have some still-working Betamax VCRs around, and even a couple Hi-Fi's too. and a Betacam. but i got tired of the novelty after awhile (plus the Beta/U-Matic U-Loading scheme is notorious for eating tapes!)
My old Betamax player is still working but my tape collections are not readable anymore. I believe the white stuff that grew inside the tape are molds and I don’t think I’d still be able to save those tapes.
Regarding efforts to save magnetic tapes regardless if they are 8-Track or Cassette Audio, BetaMax or VHS, for them to survive they MUST be stored with their spools in a vertical plane and away from heat sources.
GRAVITY SUCKS -- and many tapes quit because the mylar media has literally dropped or slid off the spools' centerline and is resting against their plastic enclosures. Aside from that, often there is nothing else wrong with them!
In theory ... a 'dead / stuck' tape that had been stored 'flat' rather than vertically could become operational again if you flipped it (again flat) and try to play it a few years from now!
2-track Commercial and 4-track Consumer 7" real-to-real tapes are perfect examples of this phenomina, where you can literally see the media coming off the Master spool twisted or on its side at a angle rather than perfectly flat. :gramps: