19-09-18, 01:10 PM
I can’t think of any reason to mark the position of the bobbins unless a previous owner was interested to see if they rotate in normal use.
I didn’t clean my bobbins for the first few pairs of discs I’ve used, but the last lot of OEMs I did and the mileage from them didn’t improve. Now on EBCs with their SD system (which can’t be rotated) and these do seem to be lasting better.