722.357 Rebuild -- stuck in first gear

[nicholas]

I just finished rebuilding this transmission and got it on the road. I didn't have reverse before and now I do. I added fluid until it showed up between the lines while running on level ground.
Two symptoms are showing up:

(1) It does not shift out of first and seems to have a very high stall limit before it hooks up.
(2) There's pressure sensor to test the modulator pressure. The pressure is only 10 psi or less when idling and driving around. Only above 3500 RPM does it get any higher (24). It's supposed to be 35 psi or so when just idling.
I've heard maybe a stuck kickdown solenoid. Should I just disconnect lead wire to test? Any other possibilities?