Stihl AV031 chainsaw cap for diagnosing no start conditions 28MM BY 25MM BY 2.0 Pitch

thingiverse

When your hat is cracked, this fix will serve as an immediate substitute. The manufacturer has included a check-valve for expansion purposes. You can print it in plastic; ABS material will swell within 5-6 days and become stubborn to remove. The vented version should be simple to create a small orifice by using a hot nail that is approximately .020 inches thick.