Better than 95% of the time it is the small reverse piston lip seal. It hardens. Then the jumpy and chatters. Then when the seal tears one looses reverse hot or cold.

Photo 7 of this thread shows you the seal-This is how you get to it-It is the same process for 722.3-722.5

Photo 10 shows all the parts you should replace, but you should replace all the springs too.

722.5 transmission oil pump rebuid DIY - Mercedes-Benz Forum

Here is a thread on the fix too:

no reverse / jerks in reverse when cold - Mercedes-Benz Forum

Some more info, and post 5 has everything you ever wanted in transmission repair:

Gearbox 722.368 repair manual / tips - Mercedes-Benz Forum

All the best,

Martin