leedsbaz

ive purchased a replacement 6 speed auto box for my 2013 focus and after fitting there is what feels like a misfire when idling. nothing shows on diagnostic and no engine light or stored faults. you can clearly feel shaking through the steering wheel and car seems reluctant to rev accompanied by noise that wasnt evident before the change. on test drive it changes fine and kickdown is fine. stop at a junction and its really lumpy. the garage has found what looks like an alignment mark on old box and thinks there may be one on the flywheel which he was not aware of and it mat be out of balance?.
has anyone any experience of these boxes as it has spent more time in workshop than my drive.