In search of 4B3A Microswitch Keyswitches (for a system restoration, not keyboarding)

I know what you guys are thinking- no, this isn't for a keyboard collection or some modern build or some other nonsense like that. I have a friend who is restoring a fairly interesting and historically significant vintage computer- The correct SD-series replacement switch would be the 4B3A- *** These can allegedly be found on some of the Diablo printing terminals.*** Subject to what /appears/ to be a batch-related encapsulation failure in the glue on the proprietary hall effect sensors, around a little over half of the switches on the current keyboard are bad. It is possible other switches ending in ***A could be made to work with a bit of labor and disassembly (swapping the fairly brittle sensors). I am not a keyboard expert but I have learned that you can remove a key on some of these microswitch keyboards and read the model fairly easily on each switch. Please let me know if you have a lead on a donor for these switches. They will be put to good use, and you can reply to me off-list for more details. Thanks.