Then I can only point to user error...
How can we use it for a whole year doing pallets of all things, lots of pine, plywood crap, nails, the bar is in the dirt half the time too...and not have a dirty gilter after probably 30 tankfulls a year. We go through, Id say...80 pallets a year, with 25 of those being crates with ply sides, that we cut upo all parts to fit inside a little old Ashley woodburning heater, nothing bigger than 10" across and 20" deep...
Once a year I pull that saw down, put on a new bar, clean the filter, tune the carb, powerwash the complete saw, etc...it doesnt get touched otherwise all year except fluids and sharpen chain.
To make matters worse, it's a saw that was used for probably 8 years by a commercial tree surgeon that they ran over with a truck and crushed the saw, my boss put the powerhead in another case, and has been using it ever since. it's been years and years.