These detailed items are for those who are technically capable of understanding them and implementing them. The reason is that it is a way to share what is determined, designed or found to need correction on the various models noted. It will allow a technician who works on tape decks to benefit from my observations and design mods to make their repairs better or more accurate.
Do not hesitate to contribute if you have a proven and tested design mod.
Tascam 122 Mk III balanced unbalanced rear small switch found. This is the original part from Alps and is called a 530C switch. Mouser has them. Part is called- https://www.mouser.com/ProductDetail/alps-alpine/sssu122200/?qs=seHrhfPpLDzySWynEduwtw%3d%3d&countrycode=US¤cycode=USD