I have strongly suggested in posts made.
That a Cart' will become very contaminated with Airborne Particulate and it would be best to have the Cart' professionally cleaned at least once during its usage life to keep the Cart's function close to optimised.
A Styli Condition check and thorough clean, will be part of such a Cleaning Service being carried out.
My observation is that 200 Hours is a point where contaminant becomes visible by the eye, as a mass collection, by 400 Hours, there is substantial collection that is built up on the critical interfaces, that can only be described as impeding to the parts needing total freedom of movement as per the design.
Metal Particulate is known to collect on a Coil Winding and successfully short the coil. causing a channel to fail.
In Good Form Styli and Cleanliness within the Cart',
are conditions that reward the user substantially.