I have done this already I removed 4 bolts on the first plate, the filter was clean, I then removed another 3 bolts and then there was nothing there, there was a few steel cogs and a half moon in the centre that seemed to spin simultaneously, everything looked fine plenty of oil and I definitely put them back together correctly aligning the holes to suit the bolts,the second 3 bolts are more difficult, the first 4 are straight forward, but I honestly know this can be very tricky because all the weep holes on each plate should be exact like a stepping motion between the plates for the oil to pass through correctly, I could have done something there although the problem was diagnosed before then and sound still is the same also...