Two problem's with these wee thing's. They were never designed to be cleaned in the first place and secondly, more and more designer's are placing them two third's of the way up the frame with a hopper above and larger main pane below. They are a wfp nightmare and impossible to clean properly using the wfp. Best anyone can do is wash them then leave a long while to drip dry, then wash the pane below. It's just not good result's any other way.
Stay clear if you don't want the hastle.