I am gradually getting my transmission "sorted out!"

I have changed my reverse/high piston and some solenoids. I should have changed all solenoids at the same time, though.

I still have one or two rough downshifts, but my upshifts are smooth now. Woo-hoo!

I have found many resources in the Mazda, Rover and VW forums for others "blessed" with the same JATCO transmission. JF506e.

I am including some random links that others may find useful:

Transmission symptoms and possible causes:
https://issuu.com/artrans/docs/shop_notes_jf506e

Great explanation of which solenoid does what.
http://forums.vwvortex.com/showthread.php?3469274-09A-Tiptronic-Solenoid-Location-Function

Changing solenoids:
http://forums.vwvortex.com/showthread.php?1521077-Solenoid-Change-09A-Tiptronic

Checking solenoids with meter:
https://www.jaguarforums.com/forum/x-type-x400-14/gearbox-fault-code-p0778-147745/

Changing reverse/high on Rover:
https://drive.google.com/file/d/0B2DhvngY-3XvZmY3ZGFjZTYtZDNmZC00NGJhLWEzNWMtNzQxNmI0ZWQ0YzE 1/view?usp=drive_web&ddrp=1&urp=http://www.the75andztclub.co.uk/forum/showpost.php&hl=en&pli=1#

 

Awesome links! This is exactly what I was looking for! My transmission shifts well between normal gear changes, but when I push the gas all the way to the floor and activate overdrive, it slams into gear. I am hoping it is the solenoids. Did you end up changing all of them? Also, where did you buy them?

Thanks!