I agree with you, jim_b, and some of the other commentators as well. What everyone seems to have missed, or at least not commented on, is the fact that in the MBZ maintenance library, mention is made that all paper filters must not be cleaned but changed, and screened filters may be cleaned. In addition and according to the original photos in this library, MBZ first presented the 110 engine and others with paper filters. So the natural conclusion is that one can use either type of filter as long as it is cleaned or changed properly.

Waiting for feedback