VW Fox 2005

Hi, I have a VW Fox 2005 with the detail that when making the changes of first, second and setback the lever of the changes becomes somewhat hard to make the change with the other speeds enter them and when moving in the flat route it works well when I take a route that is in climbs that I need more strength of the vehicle sounds like a strong bed and the speed is the speed in the second march

Check the change cables, some may be grabbed and do not finish entering the march at all.