Do I have to drain the trans fluid first? I have a faulty switch and pulled on out of a spare trans (but I don't know if that one has been drained or not) and it didn't leak out a bunch of fluid.

Just want to know before I drain the fluid for nothing, or get a face full of that great smelling gear oil.

I guess I should have searched a little more before posting.

I found some posts suggest that the switch is above the oil level of the gearbox.

There was a suggestion that the plunger could be worn down and is not as long as it should be, so the switch is not engaged. A suggested fix (beyond replacing the plunger) was to use a similarly sized drill bit with the correct length as a replacement for the plunger.