I re-visited the threads below due to the feed slowing on my Kaa-2. Even full in, it would not shove coal off of the grate. It looked like the stroke was much slower than it was when new [last year].
What I found was, pieces of gasket mat'l were caught in both sides, causing the slide to jam, which slowed the stroking. Not to mention putting much more load on the little motor. I'm un sure if the gasket mat'l was placed there to act as a seal of a sort on each side, but the mat'l ended up jammed between the plastic screws and the main body, causing drag on the slide.
I will note that there is no need to empty the hopper to remove the slide. The coal will simply shove into the grate when re-installing the slide.
On another note, there seems to be a little difference in stroke length on some of these. Hard to explain, but it looks to me that the little nub cast on the top section of the slide that the arm pushes on for the out stroke could vary in shape and size from unit to unit. In other words, between the in and out movement, there is a pause in the motion, due to clearance between the arm and the little nub. On my unit, there is apx 1/8 turn of the wheel that does nothing. If you watch the unit work, you'll see that nothing happens for a time between the in and out strokes. If someone needed more stroke, they could probably take the slide halves apart and grind said little nub to allow a little more stroke.
I'm showing the links below in case anyone has a like issue;
Keystoker KA-6 feed problem keystoker
feed problem with a keystoker kaa-2 problem keystoker