I just figured it out! Only issue now is the last section doesn't shut off output6 if I wiggle the spindle. I tried it with an or instead of 2 if statements, but it didn't work either. it won't activate if the spindle is running though, which is the main thing I wanted.
[mc.ISIG_INPUT3] = function (state)
local output6 = mc.mcSignalGetHandle(inst, mc.OSIG_OUTPUT6)
local spin0 = mc.mcSignalGetHandle(inst, mc.ISIG_SPINDLE_AT_ZERO);
local spin0state = mc.mcSignalGetState(spin0)
if(state == 1) and
(spin0state == 1) then
mc.mcSignalSetState(output6, 1)
end
if(state == 0) then
mc.mcSignalSetState(output6, 0)
end
if(spin0state == 0) then
mc.mcSignalSetState(output6, 0)
end
end,