If you've spent more than an hour or two cleaning this your either doing something wrong or don't have the right equipment.

I cleaned mine on the back of my tailgate with engine -brite cleaner a hose, Wire brush and compressed air blower. Take a screwdriver and pick at or scratch off the heavy gunk. Be sure to pick out the clumps in the spring perches other than that because the shape doesn't have any concave surfaces there really shouldn't be anything that the wire brush can't handle.

I had a coating off Road grime about an eighth inch thick in places on the tubes that came off easy with the method described above. Also it's easier to scale/screech/wire brush it Before applying the decreaser.. this way you remove the gack rather than break It down and smear it all over