Stiff 2nd Gear

I have a mk2 55 plate ford focus 2.0 TDCI,

I have noticed that 2nd gear is stiff to engage from a cold start (usually when left over night), if I put it in 2nd to fast it often makes a 'crunching' noise. Once the car has warmed up and ive changed into 2nd a few times it gets better and better? Any idea's what this may be? It's a re-con gearbox and I had a similar issue on the previous original gearbox but it was alot worse and also reverse was very difficult to engage. All other gears feel fine and 'new like' its just the 2nd gear....  (note gearbox is only about a month old and has covered little miles)...

Any advice would be appreciated!!!