Fourth gear not engaging 1994 940 Wagon

[Javisco]

Hi.

My 1994 940 wagon (non turbo) was having problems changing from 2nd to 3rd. A friend of mine rebuilds it ($600) and it's working pretty good 1, 2 and 3.....but now the 4th gear (overdrive) it is not engaging. I sent it back to the mechanic for a full review. He said it's nothing inside the transmission, maybe an electrical issue.
I had read a lot of threads about this issue and applied all of the solutions found and still not working.

-I replaced the overdrive solenoid with a new one ($100) and doesn't work; the activation click test was performed. We test with other used solenoid.

-A new Overdrive Relay ($40) doesn't work either.

-A by pass to the new solenoid was made to have a permanent solution and doesn't work.

-The kickback cable was inspected and adjusted in various ways and nothing.

Is there anything else that could cause this problem?

Thank you in advance.

[lummert]

With the bypass plate only one o-ring is used, the outer. Are you sure the inner o-ring was removed?