There was a long discussion a year or so ago, on this site, about aspirators, air cleaners and etc. NDDan, in his usual very generous manner, provided a wealth of info on the problems and fixes. A good working and fully functioning aspirator and exhaust extractor is essential to prevent regular blocking of the air filter in fine chaffy or dusty conditions. We had burnt out some of the plastic cyclone generators in the aspirator when the hood cover air cleaner screen became coated with fine barley dust and blocked the air flow to the engine. [ cummins ] The engine then sucked the hot exhaust gases back through the extractor pipe from the exhaust extractor and burnt some of the cyclone generators in the aspirator. A new aspirator was required as Donaldson have made sure that the cyclones are not replaceable. We were lucky as in a case like this, the hot gases can then burn holes through the filters and allow dirt and dust into the engine. We have also found, as Dan recommended, that it is essential to remove the aspirator each season and THOROUGHlY clean and flush with water. If we have doubts as to the possible blocking of any cyclones, we even push out the plastic screw part of the cyclones and will often find that the gaps around the cyclone generators where the dust is extracted through, are partially blocked. Dan also suggested that an access hole be cut in the aspirator body to allow inspection and to allow better cleaning under the cyclones, something that is on the mod list for us. We overcame the chaff blocking the hood screen problem, eliminated most aspirator problems and greatly increased the time between filter cleanings by removing the hood screen and extending an air cleaner tube to access clean air above the top of the grain tank. Hyper Mods- Heddy's Hyper Mods. No further problems with air cleaners since. Cheers.