Transmission does not shift from first gear to second gear upshift

Yes, my Speedometer works. I read the manual differently. I was hoping I could disconnect the wires from the outside of the transmission. Are the wires in this picture not the very same solenoid wires inside the transmission? I see some plugs and or clips that look like they may either detach from the transmission or disconnect from each other. Are one of these plugs/clips possibly the solenoid connections I was hoping to disconnect without going into the transmission? I am quite poor. I realize I may need to take that next step anyway but, if possible, I would rather drive around the farm in “manual mode” until I can come up with the funds to replace the transmission gasket and solenoids. If I do need to go into the transmission, is there a dirt poor pro tip that doesn’t destroy the gasket and a way to unstick a solenoid and therefore getting back on the road for, dare I say, the cost of my time? Stuck doesn’t sound like broke to me. I understand the potentiality of my tinkering and wishful thinking may cause a false sense of repair and only last a short time.

Thank you for your patience and time.
Rolandbk

So, I tested the two shift solenoids, one didn’t click when I applied 12volts to it. So, I carefully took it apart and didn’t see anything stuck or bound up, put it back together and no change. So, I ordered two new ones, and they should be arriving shortly. The fluid stunk like it was burnt, but there was not any metal to speak of on the magnets on the pan. I’ll let you know if it was the problem, I assume so since there wasn’t any slippage from neutral to 1st or to reverse.

The screen/filter wasn’t plugged at all from what I could see, so I didn’t replace it.

I’ve read that I shouldn’t just replace all the fluid at once. That I should replace what came out when I dropped the pan, but wait a few miles and quart by quart replace the fluid over time?

Thanks again, you guys have been more than patient and helpful!

Roland

So, I bench tested the three solenoids I could see and one of them didn’t work. I replaced all three and test drove and same issue. My service engine soon light is on as well as when I start the vehicle the automatic transmission temperature light is on as well. So, would a faulty temperature sensor cause it to do that force slow down instead of shifting into second? The transmission really seems okay because it’s such a good grab when I put it into drive or reverse.

Thank you again,
Roland

Is there any way to check if it is in fact the sensor before I throw parts at it?