I have just installed this filter wheel on a STXL-6303 but had trouble installing my existing Andover 50mm filters since they appear to be either too thick (for the screws provided) or too thin (recessed in the filter slot). The specs on this wheel only mention the 50mm diameter, but what are the requirements on filter thickness to use the screws + washers + o-rings provided? If I use a longer screw for a thicker filter, how long can I safely go without hitting the drive train? thanks, David Kirkby