[JayBrd]

I think the only good way you are going to be able to get it cleaned is to pull the rear cover. Blow air up from inside while you use a light brush to dislodge the stuff in the "stone". Not only will this keep you from contaminating you Hy-Trans, but the crap in the stone now will not settle back in while you dislodge it... Sucks with having to dump the fluid, but it might be wise any how after using a whole can of Brakleen already..

You're going to want to keep an eye on it from now on also. If you remove a bit of the material, you will create a spot for dirt ect. to settle into from here on also..

Radical move would be to pull the fender pan and drill out the top 8th or 16th of an inch too, but I'd give the scrubbing a very good try first..