The toggle switches that are available are items that fit quite a number of different transmitters, both current and discontinued. It's the same thing where a long-discontinued model engine has no true parts availability, but you can still get bearings because the bearings are of a common size and are used in a lot of current-production items. Parts specific to the engine (or transmitter in your case) are not available.
It's an unfortunate fact of life, but you have a transmitter that was discontinued nearly two decades ago. It's just not possible to offer support for all units forever. To expect such is really not realistic.
This thread has been taken as far as it can go, so I'm closing it.