On my one machine with the drop in bobbin, I pull out the bobbin case and clean after every bobbin. I only pull the needle plate a couple times a month, unless I notice build up around the feed dogs.
My other machines all have vertical bobbins and are a little less finicky than the drop in bobbin. My main quilter, the PQ1500s gets a quick brush out when I change the bobbin if I think about it, or if I notice lint build up. I pull the needle plate twice a month and clean that area when I oil the machine. Same with the VX560 and the Featherweight.
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