Overdrive does not always disengage.
1983 240 manual transmission. The overdrive always engages perfectly but sometimes does not disengage. The relay has been replaced, the OD light always goes out, and the click of the solenoid can be heard. I removed the solenoid and it snaps smartly in and out with each application of power. I changed the trans oil and this solved the problem for a short time, then back to staying engaged about one out of three times. What next?