The solenoids are the electrical side of the shifting and so in general terms erratic shifts, missed shifts, not shifting would point to a solenoid issue. Harsh shifting is the mechanical side of the shifting which is fluid pressure or the valve body which actually directs the fluid. High pressure will cause the engagement to be too fast which will be harsh. Failing/sticking valve bodies will also cause this issue.
If it were me, I would be replacing the valve body on this because they are relatively cheap. I attached the process for replacing it but I would feel pretty confident in doing this.
Let me know what think and we can go from there.
Images (Click to enlarge)
Friday, September 20th, 2019 AT 12:19 PM