Sony High 8 Tape Older tape from periods 1993-1996

Question

I have two Sony Professional High 8 Cameras that I have been using since 1991. I have also two Professional High 8 players.
I am in process of archiving all my High 8 tape to dvd
Here is the problem. I noticed that all the tape manufactured between 1993 and 1996 will no longer play on the cameras or players. The tape prior to 1993 and after 1996 plays well.
Also, when I was editing from these tapes from 1993-1996 these tapes played well. After time they have become a problem.
The symptoms of these tapes results in the screen looking like the tape head need cleaning but cleaning the heads does nothing.
I have tried different players and same results. The tapes before 1993 and after 1996 are ok. I suspect something in the tape has gone bad after a period of time.
Is there a solution? Does anyone have a player that can play these bad tapes? I am sure there are others that have now experienced same problem with High 8 from that time.
Thanks