We had out annual turning demo for the high school shop classes yesterday and during the middle of one demo, the on-off switch quit working. While we moved everyone to a different lathe, I opened the panel and blew out the switch and it worked again. It was intermittently failing after that, so I think we need a new one. It's been a while since I replaced one of these (Boy, have the prices gone up!) but I'm familiar with the replacement process. When I went to check which switch we need, I saw both ZBE-102 and ZB2-BE-02 switches mentioned. They look pretty much the same. Can someone who knows electronics tell me if one is more appropriate in a 3520A? What about a 3520B? (we have both in the high school shop, and I'll buy a spare)