I never knew you were running an air filter. I tried one of those on a flip-n-fly OS 25FX powered House of Balsa P-51D Mustang because it had no wheels and the engine was inverted (not good). I never use Tennessee-go-fasters like fuel filters, air filters, vent filters, exhaust deflectors. They cause way more problems and solve nothing. I do filter the fuel when pumped in the planes tank. I have an OS 46FX, ST 40, and Webra 50 GT that have hundreds and hundreds of flights and they still run like new.