2015 Ford Fiesta slight juddering when pulling away

There have been problems with the 2014/5 transmissions on that car .
Ford Fiesta Technical Service Bulletins (TSB)
2011-2014Fiesta – TSB 15-0090-15-0043 / 10058318
Problem:

According to Ford, certain 2011-2014 Fiesta’s that are equipped with the Ford DPS6 automatic transmission, may experience excessive transmission clutch shudder during light acceleration, and/or fluid leaks from the clutch housing. This is due to fluid contamination of the clutch, caused by failed input shaft seals.


2011-2015 Fiesta – TSB 44852 / 10057815
Problem:

If the above repair to fix clutch contamination isn’t done correctly, the new input shaft seals could swell and rupture, causing the same problem to occur again.

Solution:

When cleaning the bell housing and clutch assembly, allow ample time for the parts to dry before installing the new input shaft seals. Otherwise, the cleaning solvent can cause the new seals to swell and rupture.

Could try changing ATF , often cures a lot of faults

https://www.youtube.com/watch?v=zS121dp91YQ

Solution:

Depending on the severity of the damage, the clutch may be able to be cleaned, and both input shaft seals replaced. However, the clutch itself may need to be replaced as well.

2011-2015 Fiesta – TSB 44852 / 10057815
Problem:

If the above repair to fix clutch contamination isn’t done correctly, the new input shaft seals could swell and rupture, causing the same problem to occur again.

Solution:

When cleaning the bell housing and clutch assembly, allow ample time for the parts to dry before installing the new input shaft seals. Otherwise, the cleaning solvent can cause the new seals to swell and rupture.