Wrap the cartridge with paper towels when you install it. The cartridge filter takes about three sheets to completely wrap the filter center the filter on the paper towels roll it around and put a piece of tape on to hold it. Now take the ends fold them over and put it in your cleaner, done.
https://www.amazon.com/Shop-Vac-90304-Cartridge-Filter-Single/dp/B00002N9DQ