The rear pump drives off of the governor. Many times the spring that keeps the pump drive gear against the governor comes apart. That can cause the rolled split pin on the governor drive gear to shear-off & then you have only LOW gear.
At dealer we either replaced the complete rear pump(if customer wanted) OR just left the rear pump gears OUT, as they aren't needed for the trans to work properly. Then all you need to do is replace the "rolled pin" in the governor drive gear.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator