[Steve Tinker]

A couple of pointer before you change the fluid:
1) You will have to remove the 2 x cross braces and the triangulated chassis brace to get to the drain plug.
2) Remove the fill plug before you remove the drain plug.
3) For the very best results, only use the Porsche transmission fluid for the 6 speed box - use the search function for an hour of explanatory / fun / disagreeing reading.
4) When you have drained the old oil, let it settle and see I there is a gold or copper coloured tinge on top of the oil - possible syncho wear causing your problem.