IB5 Stiff Gear Change - not the usual.

Evening all.  Apologies for being one of those folk who joins a forum just to ask a question and glean the collective knowledge of existing members.

The chances are that I'll be here for some time to come, since Mrs Haych likes her Fiestas.

Her current 2005 1.4 Fiesta has developed a problem with the gear change.  I've Googled the problem and have found the common fault whereby the bushing on one of the sector bearings seizes up due to the joint drying out and expanding with the heat.  However, it's not the same fault, I only wish it was.

The stiff lever is the one at the bottom that moves up and down when the gear lever in the car moves side to side in the neutral position.  This lever moves freely from midway and up, but is incredibly stiff from the midway point and down.  So, from inside the car, the gear lever moves fine to the right, but move it to the left to the position necessary for 1st and second gears and it's very difficult.

I've disconnected the selector cables to be sure it's not a duff cable and have confirmed that the lever towards the bottom of the gearbox is still binding when pushing it down.  There's also an audible clunk from inside the gearbox when pushing the lever downwards.

Does this sound like a problem that necessitates a new gearbox, or is there an equally as easy fix for this as with the other lever on the box sticking?

Thanks in advance.