No upshift 1 -2. could this work?
 

Yup got no upshift from 1-2. the rest of the gears works great and have no scary sounds. so i gues the 3-4clutch are ok and sunshield.

But could it be the 2 servo pump? or solonoids?. Im gonna change the oil filter to morow. i thought i could have a looksee on this.
but little unsure if its possible.

when the filter,wiring harness is off. could i take off the vavle body( not sure what you call it in enligsh but ) or is this a big no no
i was thinking of those little steel balls flying all the way.

▪ 1-2 Shift Solenoid
▪ 2-3 Shift Solenoid
▪ 3-2 Solenoid
▪ PWM Solenoid
▪ TCC Solenoid with Harness
▪ 4L60E Superior Shift Reprogramming Kit
* 4L60E Corvette 2nd Gear Servo
▪ 4L60E Filter
* New pan with ehm so the oil can be drained when u unbolt a screw.

could i change these with out taking the 4l60e out of my blazer?
also when i put it all back. can i use some transmission grease on the check balls or is that a bad idea?

The 1-2 shift solenoid is a distinct possibility. You can test the solenoid when you have the pan off. Disconnect the electrical connector to the 1-2 shift solenoid and test the resistance of the solenoid. It should be 20-30ohms. Then, measuring the resistance from each terminal to ground should result in a resistance over 250k ohm.

The solenoid can be replaced without removing the valve body or transmission.

ok thanks gonna try that first. but if i want to open the valve body. i gues all the check balls would fall down?

The check balls should stay in the valve body. I can't recall if there is one check ball above the separator plate or not. It has been awhile since my last 4L60E shift kit install (should really do that to my Rainier). If I have time later, I can take a look in my ATSG manual to verify.