Volvo Repair: overdrive not engaging, volvo 240dl, solenoid

Question
My 1986 Volvo 240DL stopped shifting into 4th (overdrive). I've replaced the overdrive relay in the dash next to the glovebox and the overdrive solenoid on the transmission. The solenoid is being energized when the arrow on the dash is out & the power goes off when the arrow is on. What's next? I've got to get 4th (overdrive) operating.

Answer
if the solenoid is operating I would remove the solenoid and check that the orifice on the solenoid and on the transmission where the fluid goes through is not clogged.I would try using a small piece of wire to check the hole on the transmisssion.if this is ok it may be a problem inside the transmission