307 gearbox maintenance, master recommendation adana

friends, my 2004 vehicle came 170,000 km, slowly the gearbox started knocking in gear shifts does not always do when it passes from 2 to 3, falling from 3 to 2 do you just suggest a master on the island or in Mersin, or do you go to the master, change the press pads and coals, can you say anyone can do it?

I need advice, thank you from those with experience.