Hi Andrew,
I'm definitely no authority on this subject, but having just pulled the filters out of my RL200 to manually clean them, i can tell you that the seals on it are level with the inside edge and don't go over the bolt holes. I don't see an advantage of covering the holes, as the filter sits inside the holes and the seal is made between the machine and the outside edge of the filter. As for the cloth sock thing, i would just take it off and throw it in with your washing. I'm sure that will sort that one out. I'll have a look in the manual this morning when i get to work to see if i can find a part number for the brushes.
Regards,
Bryce
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https://www.brycecomerwoodworks.com/
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Bryce Comer