My first attempt at finding help. My truck's a IIa 2005 XS TD5 Man - with a sticky gear shift

I am not sure if the gearbox is still the R380. I know this was quite a notorious box for the 1- 2 shift.
It's worse on start up(cold) - takes quite an effort to shift into second.As it warms up - it gets better. It feels as if it catches - not quite in gear before it slips into second .Much less of a problem above 2500rpm .Land Rover dealer checked this out and said the tranny fluid was low....
It's driving me crazy...any ideas?
Regards