I have an Oneida DC with an internal filter. I don't think they offer these any more, and I know why. If they clog, they are a bear to clean. In fact, just normal maintenance is a big job as removing the filter for cleaning requires removing the cone. It comes off easy..
Some time back I had the bright idea that if I put a nice heavy plastic bag in the drum then the chore of emptying it might not be so bad. Well, in theory that sounds good, but in practice the bag pulls away from the sides of the drum, constricts the dropping dust, and causes everything to back up inside the cone and eventually packing in around the filter. You can see in the picture where the filter is located and how hard it is to clean around it.
It was easier to get rid of the dust - not having to dump the drum - but if I forgot to constantly check the dust level, open the drum and push things down to expand the bag, I'd have an even bigger mess.
So, time to scrounge the misc part pile. A piece of left over lexan, a few odd screws and nuts, a little caulk, and now I have a window on the world of dust. This will be easier to check and no more constricted flow. I placed the window so its top is about the 3/4 mark. Now I know if I don't see open space in the window it's time to dump. It' won't be pleasant, but it will be easier than unpacking the filter.