With the release of the 2004 PowerTrak models, the Upper-Tank Filter Frame and the Upper-Tank Filter have been heightened. The new, taller 3" Upper-Tank Filter will fit on the older size frame by condensing it and will insert into any older Upper-Tank Assembly; similarly, the older size 2 1/4" Upper-Tank Filter will fit on the new, taller Filter Frame. Note: If you have purchased a new 2004 Power Trak Model (3593-2, 3593-3, 3593-M, 3594, 3594-M, 6590-W), and have installed the older, shorter, Upper-Tank Filter onto the new, taller Filter Frame, it will create a space at the top that will cause the Clean Filter Indicator to not function properly. Because the space will allow for greater air-flow, the Clean Filter Indicator will always show green, even if the filters are dirty. The Clean Filter Indicator operates by the strength of the air-flow through the machine. Note: The part numbers for the Upper-Tank Filter (203-1085) and retail pack (3093) have not changed. If you have any questions regarding this change and which filter to use, please call Consumer Services at 1-800-263-2535, Monday - Friday 8 a.m. to 10 p.m., or Saturday 9 a.m. to 8 p.m., ET. A representative will assist you.