New beam & gear shift

[Ands1]

Had a mate fit a new beam to my van. All well apart from finding gears, before it was dead easy glided into first when at lights, now I have to yank it into 2nd & set off in that gear. Reverse crunches badly. When sat with the engine off I can glide the gear stick into all gears easily. Which leads me to think the cable might just need adjusting but why when the gears were ok before?
I beleive the gear shift rod has to come out for new beam so I thought he might of moved the plate in the cab floor but I can get gears way when sat with engine off.
Any advice? Thanks