The Watkins copicat Mk1&2 doesnt have an erase head , it uses a magnet to erase the tape ,
depending on the strenght and proximity of the magnet it erases the previous take more or less , but some ghost echo does make it back around .
Two small flat Ndym bar magnets placed in close proximity to the tape , inside the shell , would probably adequately erase the previous dub , the tape having passing twice across the magnets when you flip it over to record on the otherside .
Theres sometimes suitable magnets to be found in retail packaging boxes ,like for instance mobile electronic accessories . Generally not a great idea to be putting strong magnets in the vicinity of the heads ,but you can always demag if the need arrises . there could be other possible issues like the casstte tape not sitting right due to the pull of the magnets ,who knows , but it might be worth a try to avoid the need to modify the basic tape path geometry and each precious cassette tape .
I biterly regret not buying up a bigger supply of blank cassettes when the hifi industry was dumping them for 25 cent a piece , I was the man in the Hifi shop who sold them and I forgot to keep some for myself in the end .
Theres nothing like the sound of fresh tape .....
