ive finally got hold of a second hand torque converter but its got a bit of sand or somthing on it im not sure if its inside how can i clean it to make sure???

The only way to clean a torque converter is to cut it in half, wash it thouroughly, weld it back together. If you use a dirty torque converter, it will pump all the crap that's in it around your gearbox and kill it. This is the mistake people make fitting replacement autobox's with there old torque converter, and vice versa