I've been helping a buddy with his '88 240. The transmission wasn't going into overdrive and I discovered it had a dead solenoid. I ground a channel between the two orifices in the solenoid and reinstalled it with a new outer o-ring (I've done this several times in the past with good results) When I test drove the car, it was sort of slow to go into 4th, but it did go when I hit about 50 mph and would drop down to 3rd when the kickdown was engaged. Now, about a week later, it won't go into 4th at all. What would cause this in an AW70? I fear my buddy may need a new tranny. This one has 200+K on it....

The fluid is OK, but I haven't tried a flush or pulling the pan to check the filter screen, but they are usually so clean I wonder if it's worth it.

The kickdown cable is adjusted properly.

Any ideas?

Thanks!