Hi GT,
In my instance, the feed chute had to be cut. It was necessary to enable the pucks to come clear of the chute. Before I notched the chute, the puck to be burnt would be left laying on the chute by about 3/16ths". As a result the pucks would begin to burn on one end before the other and in 20 minutes the burn was not complete. As the pucks shuffle along every 20 minutes they are in contact with each other, (one pushes another). The burning pucks trailing edge was always in contact with the next puck in line to burn. The late ignition of the burning pucks trailing edge, (laying on chute) was enough to ignite the next puck before it's time so when the second puck was pushed onto the burner it was already burning on its now leading edge. So the problem just escalates as you burn more pucks. The leading edges ignite faster and faster and burns beyond the designed amount and the trailing edges continue to ignite too soon.
There may be other ways to alter or adjust the feed mechanism to ensure the puck is pushed completely on to the burner however I did not want to mess with the travel arm adjustment or micro switch to find out. Cutting out the feed chute seemed simpler and logical.
As far as lowering the burn plate, that only made sense to me. This way the pucks drop down and some distance, (3/16") is put between the chute and burner. Although the pucks are still in contact to maintain the proper push the area of contact is less as the burning puck sits lower. This means the puck has to be well into its burn before it can begin to ignite the puck adjacent to it. This way pucks are not burning before their time. It's only two little screws that retain the burner and you have to undo them to notch the chute so why not change them out with slightly longer and place a few washers between the chute and burner while you are in there.
I would expect a puck to burn reasonably evenly and to the correct degree within its 20 minute slot. This was definitely not the case in my machine. You can easily hook all your cords up with the smoke generator sitting beside the cabinet and use the puck advance button to cycle them through to see for yourself how your unit is operating. I don't think they all do what mine was doing but with several variables (including assembly tolerances) affecting puck travel and final placement some are experiences the same results as I was.