1990 Automatic: Overdride Solenoid?

[TheOneEyedBandit]

I've got no overdrive. The overdrive light stays on almost all the time; occasionally it will go darker, brighter, or out when the switch is depressed. Usually, though, the light just stays on all the time. I can hear the relay click when the switch is depressed, and there is voltage at the solenoid itself. All this tells me that the problem is the solenoid, but I'm not really confident about my limited transmission knowledge, and I want to see if you folks agree before I go lay under the damn thing and get a face full of transmission fluid.
So. Reckon it's the solenoid?

Thanks

Joe