Someone please help...

I have a 1990 240 wagon that will not go into 4th gear, I have read many threads about this problem. But none really help me.

This is what I have already checked or changed to try to fix the problem.

1) The OD light turns on and off.
2) I have replaced the OD solenoid and bench tested it. I applied 12 volts to it
and it clicked.
3) I checked the wiring.
4) After replacing the solenoid, I listened under the car while I pressed the OD
switch. I hear a clicking sound under the car. After this I road tested the
car and still have no 4th gear.
5) Then I drained the transmission fluid and cleaned the pan.
6) I flushed the whole system via a method I read here on this web-site.
7) Then I road tested the car, no 4th gear...

I don't know what to do next. One post from 1997 stated that the solenoid is normally closed and will by default give you the 4th gear.
If I disconnect the wire to the solenoid, will I have a 4th gear?

I promise if someone can help me with this problem I will join the BrickBoard.
I have already spend lots of money trying to solve this problem. I really would like my 4th gear back.

Thanks sooooo much!!!!