grinding 2nd gear in ford transit t260 03 plate?

when i select second gear i sometimes get a crunching grinding noise? what could be the cause of this? when i do change to second for it to select the gear i have to force it down quite aggressively. also i went under my van and took off the black box directly under the gear stick as i had been told that sometimes under there they seize and found the two pulleys that change gear that have a gold plate above them which has a thread for a bolt that looks like it ties the two together but it doesnt have anything in it should it have one? could this be the cause of grinding?