Gearbox Problem ? 2001 Transit Tourneo GLX Minibus?

About 6 month ago I lost all gears apart from 3rd, my garage repaired the problem which turned out to be the selector cost of part £120 plus fitting. Since that point onward the 2nd gear has increasingly started to pop out while driving but I have managed to put up with it as its only at very low speeds this happens. However this week I'm getting a sharpe clunking noise when 3rd gear engagers when driving. Has anyone got any notions regarding this!