Need help with a shift issue. 2nd, 3rd overdrive work fine, no slip. When starting in first its almost no go, very little pressure. It will manually shift to 2nd, 3rd, then overdrive fine. When slowing down at highway speeds it will auto downshift to 2nd and then shift normal to 3 and OD. If it ever downshifts to 1st its a no shift no go situation. Reverse works fine.

No check engine lights or codes.

I've replaced the governor solenoid and the tail shaft speed sensor. A pressure gauge on the test port shows 190 lbs in reverse. Almost no pressure in 1st. 180lbs in 2nd or 3rd.

Any ideas on the cause of this malfunction?
It happened suddenly or at least the observable symptom of complete failure of 1st was sudden and complete. Small amount of fine particles in pan magnet nothing big.

Thanks for any help in advance....

 

Have you adjusted your bands?