Primary filter 1/2
1. Small holes or perforations have developed in primary filters.
2. There is a problem with a seal in the primary filter/filter sock mounting platform assembly.
If when inspected, it is found that there is dust building up on the secondary filter, removal of the primary filters and checking for small holes or perforations in the filters is recommended.
Primary filter 2/2
Usually, small holes will begin to develop around the stitching of the filter media. If small holes are located, clean area around hole with either compressed air or vacuum. Once area is clean, the hole can be repaired with silicone sealant.
Generally speaking, with consistent use, the primary filters should be replaced approximately every 6 months. This will maintain good suction levels and reduce incidence of holes developing in the filters.