Gearstick resists moving right

[trotters]

The resistance moving the gearstick to the right (5th/6th gear) seems to be increasing. Moving it to the left is fine and I've got no trouble getting it into gear once I've moved it to the right. Google seems to only tell me about difficulty getting into gear (which isn't my problem). I'm going to take it to a garage to get checked out. Any ideas what I could expect to hear?

Cheers