Mercedes Benz repair: transmission, mercedes 420sel, forward gears

Question
1988 mercedes 420SEL V8
TRANSMISSION WILL NOT SHIFT INTO REVERSE .
What are possible causes ?

Shifts into all forward gears good .
Linkage OK .
Vacume line OK .
Fluid level OK .

Answer
I hope reading these threads helps you.

http://www.mercedesshop.com/shopforum/showthread.php3?p=737049#post737049

http://www.mercedesshop.com/shopforum/showthread.php3?p=993281#post993281

http://www.mercedesshop.com/shopforum/showthread.php3?p=993585#post993585

http://www.mercedesshop.com/shopforum/showthread.php3?p=671508#post671508

http://www.mercedesshop.com/shopforum/showthread.php3?p=629130#post629130

http://www.mercedesshop.com/shopforum/showthread.php3?p=963365#post963365

http://www.mercedesshop.com/shopforum/showthread.php3?p=961430#post961430

http://www.mercedesshop.com/shopforum/showthread.php3?p=881198#post881198

http://www.mercedesshop.com/shopforum/showthread.php3?p=762982#post762982