Purchased a rare autococker from a lad I was trying to help on pbnation. He had gotten it for cheap ($50) and I handed him a tidy profit ($200). Other than the obvious timing issues, the original owner said he had problems getting it up to the required velocity. The rear velocity adjuster was screwed in to the max so I knew something was wrong.
I tore it apart as I do with all used markers when I get them and found that the valve retaining nut was not tightened down correctly and the valve was sitting in the marker sideways and forward... no wonder balls were just rolling out the barrel. I ended up having to use a dowel to knock it out from the front of the marker as it was wedged in there with gunk.