the pass is clear, if you slam them in, it will read and drop in box. If you place them in normally they they go to the return, some fall to the box but no time is counted.
Seriously, title your threads with something more descriptive so people will read it and give suggestions. It's also good forum etiquette and makes it easier to search by... y'know... title.
We have SlugBuster 3s in an old carwash. Sometimes you need to remove and reseat the sample coin. The other issue can be that the clip holding the coin shute together comes loose such that coins do not register. We use tape or a three sided small paper clip to clamp the sides together. Not ideal but reality.